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ext4: Fix BUG_ON in ext4_bread when write quota data

PATCH Superseded Ye Bin 3 participants 5 messages Dec 22, 2021 ext4 file system

v1 of 2 Superseded Latest is v2 →

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PATCH 1/1 ext4: Fix BUG_ON in ext4_bread when write quota data

We got issue as follows when run syzkaller:

[  167.936972] EXT4-fs error (device loop0): __ext4_remount:6314: comm rep: Abort forced by user
[  167.938306] EXT4-fs (loop0): Remounting filesystem read-only
[  167.981637] Assertion failure in ext4_getblk() at fs/ext4/inode.c:847: '(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) || handle != NULL || create == 0'
[  167.983601] ------------[ cut here ]------------
[  167.984245] kernel BUG at fs/ext4/inode.c:847!
[  167.984882] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[  167.985624] CPU: 7 PID: 2290 Comm: rep Tainted: G    B             5.16.0-rc5-next-20211217+ #123
[  167.986823] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
[  167.988590] RIP: 0010:ext4_getblk+0x17e/0x504
[  167.989189] Code: c6 01 74 28 49 c7 c0 a0 a3 5c 9b b9 4f 03 00 00 48 c7 c2 80 9c 5c 9b 48 c7 c6 40 b6 5c 9b 48 c7 c7 20 a4 5c 9b e8 77 e3 fd ff <0f> 0b 8b 04 244
[  167.991679] RSP: 0018:ffff8881736f7398 EFLAGS: 00010282
[  167.992385] RAX: 0000000000000094 RBX: 1ffff1102e6dee75 RCX: 0000000000000000
[  167.993337] RDX: 0000000000000001 RSI: ffffffff9b6e29e0 RDI: ffffed102e6dee66
[  167.994292] RBP: ffff88816a076210 R08: 0000000000000094 R09: ffffed107363fa09
[  167.995252] R10: ffff88839b1fd047 R11: ffffed107363fa08 R12: ffff88816a0761e8
[  167.996205] R13: 0000000000000000 R14: 0000000000000021 R15: 0000000000000001
[  167.997158] FS:  00007f6a1428c740(0000) GS:ffff88839b000000(0000) knlGS:0000000000000000
[  167.998238] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  167.999025] CR2: 00007f6a140716c8 CR3: 0000000133216000 CR4: 00000000000006e0
[  167.999987] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  168.000944] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  168.001899] Call Trace:
[  168.002235]  <TASK>
[  168.007167]  ext4_bread+0xd/0x53
[  168.007612]  ext4_quota_write+0x20c/0x5c0
[  168.010457]  write_blk+0x100/0x220
[  168.010944]  remove_free_dqentry+0x1c6/0x440
[  168.011525]  free_dqentry.isra.0+0x565/0x830
[  168.012133]  remove_tree+0x318/0x6d0
[  168.014744]  remove_tree+0x1eb/0x6d0
[  168.017346]  remove_tree+0x1eb/0x6d0
[  168.019969]  remove_tree+0x1eb/0x6d0
[  168.022128]  qtree_release_dquot+0x291/0x340
[  168.023297]  v2_release_dquot+0xce/0x120
[  168.023847]  dquot_release+0x197/0x3e0
[  168.024358]  ext4_release_dquot+0x22a/0x2d0
[  168.024932]  dqput.part.0+0x1c9/0x900
[  168.025430]  __dquot_drop+0x120/0x190
[  168.025942]  ext4_clear_inode+0x86/0x220
[  168.026472]  ext4_evict_inode+0x9e8/0xa22
[  168.028200]  evict+0x29e/0x4f0
[  168.028625]  dispose_list+0x102/0x1f0
[  168.029148]  evict_inodes+0x2c1/0x3e0
[  168.030188]  generic_shutdown_super+0xa4/0x3b0
[  168.030817]  kill_block_super+0x95/0xd0
[  168.031360]  deactivate_locked_super+0x85/0xd0
[  168.031977]  cleanup_mnt+0x2bc/0x480
[  168.033062]  task_work_run+0xd1/0x170
[  168.033565]  do_exit+0xa4f/0x2b50
[  168.037155]  do_group_exit+0xef/0x2d0
[  168.037666]  __x64_sys_exit_group+0x3a/0x50
[  168.038237]  do_syscall_64+0x3b/0x90
[  168.038751]  entry_SYSCALL_64_after_hwframe+0x44/0xae

In order to reproduce this problem, the following conditions need to be met:
1. Ext4 filesystem with no journal;
2. Filesystem image with incorrect quota data;
3. Abort filesystem forced by user;
4. umount filesystem;

As in ext4_quota_write:
...

         if (EXT4_SB(sb)->s_journal && !handle) {
                 ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
                         " cancelled because transaction is not started",
                         (unsigned long long)off, (unsigned long long)len);
                 return -EIO;
         }

...
We only check handle if NULL when filesystem has journal. There is need check handle if NULL even when filesystem has no journal.

Signed-off-by Ye Bin <[email protected]>
---
 fs/ext4/super.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
fs/ext4/super.c +3 -2
index 071b7b3c5678..c8ca5811ea65 100644
@@ -6955,9 +6955,10 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
 	struct buffer_head *bh;
 	handle_t *handle = journal_current_handle();
 
-	if (EXT4_SB(sb)->s_journal && !handle) {
+	if (!handle) {
 		ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
-			" cancelled because transaction is not started",
+			" cancelled because transaction is not started"
+			" or filesystem is abort forced by user",
 			(unsigned long long)off, (unsigned long long)len);
 		return -EIO;
 	}
Signature · 1 line
2.31.1
#1 lore raw
Quoted 83 lines · Ye Bin

We got issue as follows when run syzkaller:

[  167.936972] EXT4-fs error (device loop0): __ext4_remount:6314: comm rep: Abort forced by user
[  167.938306] EXT4-fs (loop0): Remounting filesystem read-only
[  167.981637] Assertion failure in ext4_getblk() at fs/ext4/inode.c:847: '(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) || handle != NULL || create == 0'
[  167.983601] ------------[ cut here ]------------
[  167.984245] kernel BUG at fs/ext4/inode.c:847!
[  167.984882] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[  167.985624] CPU: 7 PID: 2290 Comm: rep Tainted: G    B             5.16.0-rc5-next-20211217+ #123
[  167.986823] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
[  167.988590] RIP: 0010:ext4_getblk+0x17e/0x504
[  167.989189] Code: c6 01 74 28 49 c7 c0 a0 a3 5c 9b b9 4f 03 00 00 48 c7 c2 80 9c 5c 9b 48 c7 c6 40 b6 5c 9b 48 c7 c7 20 a4 5c 9b e8 77 e3 fd ff <0f> 0b 8b 04 244
[  167.991679] RSP: 0018:ffff8881736f7398 EFLAGS: 00010282
[  167.992385] RAX: 0000000000000094 RBX: 1ffff1102e6dee75 RCX: 0000000000000000
[  167.993337] RDX: 0000000000000001 RSI: ffffffff9b6e29e0 RDI: ffffed102e6dee66
[  167.994292] RBP: ffff88816a076210 R08: 0000000000000094 R09: ffffed107363fa09
[  167.995252] R10: ffff88839b1fd047 R11: ffffed107363fa08 R12: ffff88816a0761e8
[  167.996205] R13: 0000000000000000 R14: 0000000000000021 R15: 0000000000000001
[  167.997158] FS:  00007f6a1428c740(0000) GS:ffff88839b000000(0000) knlGS:0000000000000000
[  167.998238] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  167.999025] CR2: 00007f6a140716c8 CR3: 0000000133216000 CR4: 00000000000006e0
[  167.999987] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  168.000944] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  168.001899] Call Trace:
[  168.002235]  <TASK>
[  168.007167]  ext4_bread+0xd/0x53
[  168.007612]  ext4_quota_write+0x20c/0x5c0
[  168.010457]  write_blk+0x100/0x220
[  168.010944]  remove_free_dqentry+0x1c6/0x440
[  168.011525]  free_dqentry.isra.0+0x565/0x830
[  168.012133]  remove_tree+0x318/0x6d0
[  168.014744]  remove_tree+0x1eb/0x6d0
[  168.017346]  remove_tree+0x1eb/0x6d0
[  168.019969]  remove_tree+0x1eb/0x6d0
[  168.022128]  qtree_release_dquot+0x291/0x340
[  168.023297]  v2_release_dquot+0xce/0x120
[  168.023847]  dquot_release+0x197/0x3e0
[  168.024358]  ext4_release_dquot+0x22a/0x2d0
[  168.024932]  dqput.part.0+0x1c9/0x900
[  168.025430]  __dquot_drop+0x120/0x190
[  168.025942]  ext4_clear_inode+0x86/0x220
[  168.026472]  ext4_evict_inode+0x9e8/0xa22
[  168.028200]  evict+0x29e/0x4f0
[  168.028625]  dispose_list+0x102/0x1f0
[  168.029148]  evict_inodes+0x2c1/0x3e0
[  168.030188]  generic_shutdown_super+0xa4/0x3b0
[  168.030817]  kill_block_super+0x95/0xd0
[  168.031360]  deactivate_locked_super+0x85/0xd0
[  168.031977]  cleanup_mnt+0x2bc/0x480
[  168.033062]  task_work_run+0xd1/0x170
[  168.033565]  do_exit+0xa4f/0x2b50
[  168.037155]  do_group_exit+0xef/0x2d0
[  168.037666]  __x64_sys_exit_group+0x3a/0x50
[  168.038237]  do_syscall_64+0x3b/0x90
[  168.038751]  entry_SYSCALL_64_after_hwframe+0x44/0xae

In order to reproduce this problem, the following conditions need to be met:
1. Ext4 filesystem with no journal;
2. Filesystem image with incorrect quota data;
3. Abort filesystem forced by user;
4. umount filesystem;

As in ext4_quota_write:
...

         if (EXT4_SB(sb)->s_journal && !handle) {
                 ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
                         " cancelled because transaction is not started",
                         (unsigned long long)off, (unsigned long long)len);
                 return -EIO;
         }

...
We only check handle if NULL when filesystem has journal. There is need check handle if NULL even when filesystem has no journal.

Signed-off-by Ye Bin <[email protected]>
---
 fs/ext4/super.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
fs/ext4/super.c +0 -0
index 071b7b3c5678..c8ca5811ea65 100644

fs/ext4/super.c static ssize_t ext4_quota_write(struct super_block *sb, int type, · line 6961

Quoted 9 lines
fs/ext4/super.c +3 -2
@@ -6955,9 +6955,10 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
 	struct buffer_head *bh;
 	handle_t *handle = journal_current_handle();
 
-	if (EXT4_SB(sb)->s_journal && !handle) {
+	if (!handle) {
 		ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
-			" cancelled because transaction is not started",
+			" cancelled because transaction is not started"
+			" or filesystem is abort forced by user",

The patch looks good, except this sentence. I don't think it has anything to do with the abort forced by the user. Yes, in your reproducer you induced the error by aborting the fs, but it can happen any time we fail to start a journal transaction. So IMO the message is already accurate enough. See ext4_release_dquot().

Thanks!
-Lukas

Quoted 6 lines
fs/ext4/super.c +0 -0
 			(unsigned long long)off, (unsigned long long)len);
 		return -EIO;
 	}
Signature · 1 line
2.31.1
reviewer
#2 lore raw
In reply to Ye Bin
Quoted 69 lines · Ye Bin

We got issue as follows when run syzkaller:

[  167.936972] EXT4-fs error (device loop0): __ext4_remount:6314: comm rep: Abort forced by user
[  167.938306] EXT4-fs (loop0): Remounting filesystem read-only
[  167.981637] Assertion failure in ext4_getblk() at fs/ext4/inode.c:847: '(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) || handle != NULL || create == 0'
[  167.983601] ------------[ cut here ]------------
[  167.984245] kernel BUG at fs/ext4/inode.c:847!
[  167.984882] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[  167.985624] CPU: 7 PID: 2290 Comm: rep Tainted: G    B             5.16.0-rc5-next-20211217+ #123
[  167.986823] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
[  167.988590] RIP: 0010:ext4_getblk+0x17e/0x504
[  167.989189] Code: c6 01 74 28 49 c7 c0 a0 a3 5c 9b b9 4f 03 00 00 48 c7 c2 80 9c 5c 9b 48 c7 c6 40 b6 5c 9b 48 c7 c7 20 a4 5c 9b e8 77 e3 fd ff <0f> 0b 8b 04 244
[  167.991679] RSP: 0018:ffff8881736f7398 EFLAGS: 00010282
[  167.992385] RAX: 0000000000000094 RBX: 1ffff1102e6dee75 RCX: 0000000000000000
[  167.993337] RDX: 0000000000000001 RSI: ffffffff9b6e29e0 RDI: ffffed102e6dee66
[  167.994292] RBP: ffff88816a076210 R08: 0000000000000094 R09: ffffed107363fa09
[  167.995252] R10: ffff88839b1fd047 R11: ffffed107363fa08 R12: ffff88816a0761e8
[  167.996205] R13: 0000000000000000 R14: 0000000000000021 R15: 0000000000000001
[  167.997158] FS:  00007f6a1428c740(0000) GS:ffff88839b000000(0000) knlGS:0000000000000000
[  167.998238] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  167.999025] CR2: 00007f6a140716c8 CR3: 0000000133216000 CR4: 00000000000006e0
[  167.999987] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  168.000944] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  168.001899] Call Trace:
[  168.002235]  <TASK>
[  168.007167]  ext4_bread+0xd/0x53
[  168.007612]  ext4_quota_write+0x20c/0x5c0
[  168.010457]  write_blk+0x100/0x220
[  168.010944]  remove_free_dqentry+0x1c6/0x440
[  168.011525]  free_dqentry.isra.0+0x565/0x830
[  168.012133]  remove_tree+0x318/0x6d0
[  168.014744]  remove_tree+0x1eb/0x6d0
[  168.017346]  remove_tree+0x1eb/0x6d0
[  168.019969]  remove_tree+0x1eb/0x6d0
[  168.022128]  qtree_release_dquot+0x291/0x340
[  168.023297]  v2_release_dquot+0xce/0x120
[  168.023847]  dquot_release+0x197/0x3e0
[  168.024358]  ext4_release_dquot+0x22a/0x2d0
[  168.024932]  dqput.part.0+0x1c9/0x900
[  168.025430]  __dquot_drop+0x120/0x190
[  168.025942]  ext4_clear_inode+0x86/0x220
[  168.026472]  ext4_evict_inode+0x9e8/0xa22
[  168.028200]  evict+0x29e/0x4f0
[  168.028625]  dispose_list+0x102/0x1f0
[  168.029148]  evict_inodes+0x2c1/0x3e0
[  168.030188]  generic_shutdown_super+0xa4/0x3b0
[  168.030817]  kill_block_super+0x95/0xd0
[  168.031360]  deactivate_locked_super+0x85/0xd0
[  168.031977]  cleanup_mnt+0x2bc/0x480
[  168.033062]  task_work_run+0xd1/0x170
[  168.033565]  do_exit+0xa4f/0x2b50
[  168.037155]  do_group_exit+0xef/0x2d0
[  168.037666]  __x64_sys_exit_group+0x3a/0x50
[  168.038237]  do_syscall_64+0x3b/0x90
[  168.038751]  entry_SYSCALL_64_after_hwframe+0x44/0xae

In order to reproduce this problem, the following conditions need to be met:
1. Ext4 filesystem with no journal;
2. Filesystem image with incorrect quota data;
3. Abort filesystem forced by user;
4. umount filesystem;

As in ext4_quota_write:
...

         if (EXT4_SB(sb)->s_journal && !handle) {
                 ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
                         " cancelled because transaction is not started",
                         (unsigned long long)off, (unsigned long long)len);
                 return -EIO;
         }
Quoted 3 lines

...
We only check handle if NULL when filesystem has journal. There is need check handle if NULL even when filesystem has no journal.

Hum, so I think we can just drop this whole condition and warning and instead add a silent return of -EROFS if the filesystem is readonly. That should also fix the bug and also make aborted case less noisy. The message from ext4_quota_write() IMO is not very useful and ext4_bread() will provide us with a BUG and stacktrace which is better for debugging what went wrong anyway.

Honza

Quoted 26 lines
Signed-off-by Ye Bin <[email protected]>
---
 fs/ext4/super.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
fs/ext4/super.c +3 -2
index 071b7b3c5678..c8ca5811ea65 100644
@@ -6955,9 +6955,10 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
 	struct buffer_head *bh;
 	handle_t *handle = journal_current_handle();
 
-	if (EXT4_SB(sb)->s_journal && !handle) {
+	if (!handle) {
 		ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
-			" cancelled because transaction is not started",
+			" cancelled because transaction is not started"
+			" or filesystem is abort forced by user",
 			(unsigned long long)off, (unsigned long long)len);
 		return -EIO;
 	}
Signature · 1 line
2.31.1
Signature · 2 lines
Jan Kara <[email protected]>
SUSE Labs, CR
#3 lore raw
Quoted 74 lines · Jan Kara
Quoted 69 lines · Ye Bin

We got issue as follows when run syzkaller:

[  167.936972] EXT4-fs error (device loop0): __ext4_remount:6314: comm rep: Abort forced by user
[  167.938306] EXT4-fs (loop0): Remounting filesystem read-only
[  167.981637] Assertion failure in ext4_getblk() at fs/ext4/inode.c:847: '(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) || handle != NULL || create == 0'
[  167.983601] ------------[ cut here ]------------
[  167.984245] kernel BUG at fs/ext4/inode.c:847!
[  167.984882] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[  167.985624] CPU: 7 PID: 2290 Comm: rep Tainted: G    B             5.16.0-rc5-next-20211217+ #123
[  167.986823] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
[  167.988590] RIP: 0010:ext4_getblk+0x17e/0x504
[  167.989189] Code: c6 01 74 28 49 c7 c0 a0 a3 5c 9b b9 4f 03 00 00 48 c7 c2 80 9c 5c 9b 48 c7 c6 40 b6 5c 9b 48 c7 c7 20 a4 5c 9b e8 77 e3 fd ff <0f> 0b 8b 04 244
[  167.991679] RSP: 0018:ffff8881736f7398 EFLAGS: 00010282
[  167.992385] RAX: 0000000000000094 RBX: 1ffff1102e6dee75 RCX: 0000000000000000
[  167.993337] RDX: 0000000000000001 RSI: ffffffff9b6e29e0 RDI: ffffed102e6dee66
[  167.994292] RBP: ffff88816a076210 R08: 0000000000000094 R09: ffffed107363fa09
[  167.995252] R10: ffff88839b1fd047 R11: ffffed107363fa08 R12: ffff88816a0761e8
[  167.996205] R13: 0000000000000000 R14: 0000000000000021 R15: 0000000000000001
[  167.997158] FS:  00007f6a1428c740(0000) GS:ffff88839b000000(0000) knlGS:0000000000000000
[  167.998238] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  167.999025] CR2: 00007f6a140716c8 CR3: 0000000133216000 CR4: 00000000000006e0
[  167.999987] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  168.000944] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  168.001899] Call Trace:
[  168.002235]  <TASK>
[  168.007167]  ext4_bread+0xd/0x53
[  168.007612]  ext4_quota_write+0x20c/0x5c0
[  168.010457]  write_blk+0x100/0x220
[  168.010944]  remove_free_dqentry+0x1c6/0x440
[  168.011525]  free_dqentry.isra.0+0x565/0x830
[  168.012133]  remove_tree+0x318/0x6d0
[  168.014744]  remove_tree+0x1eb/0x6d0
[  168.017346]  remove_tree+0x1eb/0x6d0
[  168.019969]  remove_tree+0x1eb/0x6d0
[  168.022128]  qtree_release_dquot+0x291/0x340
[  168.023297]  v2_release_dquot+0xce/0x120
[  168.023847]  dquot_release+0x197/0x3e0
[  168.024358]  ext4_release_dquot+0x22a/0x2d0
[  168.024932]  dqput.part.0+0x1c9/0x900
[  168.025430]  __dquot_drop+0x120/0x190
[  168.025942]  ext4_clear_inode+0x86/0x220
[  168.026472]  ext4_evict_inode+0x9e8/0xa22
[  168.028200]  evict+0x29e/0x4f0
[  168.028625]  dispose_list+0x102/0x1f0
[  168.029148]  evict_inodes+0x2c1/0x3e0
[  168.030188]  generic_shutdown_super+0xa4/0x3b0
[  168.030817]  kill_block_super+0x95/0xd0
[  168.031360]  deactivate_locked_super+0x85/0xd0
[  168.031977]  cleanup_mnt+0x2bc/0x480
[  168.033062]  task_work_run+0xd1/0x170
[  168.033565]  do_exit+0xa4f/0x2b50
[  168.037155]  do_group_exit+0xef/0x2d0
[  168.037666]  __x64_sys_exit_group+0x3a/0x50
[  168.038237]  do_syscall_64+0x3b/0x90
[  168.038751]  entry_SYSCALL_64_after_hwframe+0x44/0xae

In order to reproduce this problem, the following conditions need to be met:
1. Ext4 filesystem with no journal;
2. Filesystem image with incorrect quota data;
3. Abort filesystem forced by user;
4. umount filesystem;

As in ext4_quota_write:
...

         if (EXT4_SB(sb)->s_journal && !handle) {
                 ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
                         " cancelled because transaction is not started",
                         (unsigned long long)off, (unsigned long long)len);
                 return -EIO;
         }
Quoted 3 lines

...
We only check handle if NULL when filesystem has journal. There is need check handle if NULL even when filesystem has no journal.

Quoted 6 lines

Hum, so I think we can just drop this whole condition and warning and instead add a silent return of -EROFS if the filesystem is readonly. That should also fix the bug and also make aborted case less noisy. The message from ext4_quota_write() IMO is not very useful and ext4_bread() will provide us with a BUG and stacktrace which is better for debugging what went wrong anyway.

Can we really only get here when the fs is read only ? We're going to end up with NULL handle here any time the ext4_journal_start() fails in ext4_release_dquot() which I think can fail for plenty of reasons, not just EROFS.

-Lukas

Quoted 33 lines

Honza

Quoted 26 lines
Signed-off-by Ye Bin <[email protected]>
---
 fs/ext4/super.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
fs/ext4/super.c +3 -2
index 071b7b3c5678..c8ca5811ea65 100644
@@ -6955,9 +6955,10 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
 	struct buffer_head *bh;
 	handle_t *handle = journal_current_handle();
 
-	if (EXT4_SB(sb)->s_journal && !handle) {
+	if (!handle) {
 		ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
-			" cancelled because transaction is not started",
+			" cancelled because transaction is not started"
+			" or filesystem is abort forced by user",
 			(unsigned long long)off, (unsigned long long)len);
 		return -EIO;
 	}
Signature · 1 line
2.31.1
Signature · 2 lines
Jan Kara <[email protected]>
SUSE Labs, CR
reviewer
#4 lore raw
Quoted 82 lines · Lukas Czerner
Quoted 74 lines · Jan Kara
Quoted 69 lines · Ye Bin

We got issue as follows when run syzkaller:

[  167.936972] EXT4-fs error (device loop0): __ext4_remount:6314: comm rep: Abort forced by user
[  167.938306] EXT4-fs (loop0): Remounting filesystem read-only
[  167.981637] Assertion failure in ext4_getblk() at fs/ext4/inode.c:847: '(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) || handle != NULL || create == 0'
[  167.983601] ------------[ cut here ]------------
[  167.984245] kernel BUG at fs/ext4/inode.c:847!
[  167.984882] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[  167.985624] CPU: 7 PID: 2290 Comm: rep Tainted: G    B             5.16.0-rc5-next-20211217+ #123
[  167.986823] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
[  167.988590] RIP: 0010:ext4_getblk+0x17e/0x504
[  167.989189] Code: c6 01 74 28 49 c7 c0 a0 a3 5c 9b b9 4f 03 00 00 48 c7 c2 80 9c 5c 9b 48 c7 c6 40 b6 5c 9b 48 c7 c7 20 a4 5c 9b e8 77 e3 fd ff <0f> 0b 8b 04 244
[  167.991679] RSP: 0018:ffff8881736f7398 EFLAGS: 00010282
[  167.992385] RAX: 0000000000000094 RBX: 1ffff1102e6dee75 RCX: 0000000000000000
[  167.993337] RDX: 0000000000000001 RSI: ffffffff9b6e29e0 RDI: ffffed102e6dee66
[  167.994292] RBP: ffff88816a076210 R08: 0000000000000094 R09: ffffed107363fa09
[  167.995252] R10: ffff88839b1fd047 R11: ffffed107363fa08 R12: ffff88816a0761e8
[  167.996205] R13: 0000000000000000 R14: 0000000000000021 R15: 0000000000000001
[  167.997158] FS:  00007f6a1428c740(0000) GS:ffff88839b000000(0000) knlGS:0000000000000000
[  167.998238] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  167.999025] CR2: 00007f6a140716c8 CR3: 0000000133216000 CR4: 00000000000006e0
[  167.999987] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  168.000944] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  168.001899] Call Trace:
[  168.002235]  <TASK>
[  168.007167]  ext4_bread+0xd/0x53
[  168.007612]  ext4_quota_write+0x20c/0x5c0
[  168.010457]  write_blk+0x100/0x220
[  168.010944]  remove_free_dqentry+0x1c6/0x440
[  168.011525]  free_dqentry.isra.0+0x565/0x830
[  168.012133]  remove_tree+0x318/0x6d0
[  168.014744]  remove_tree+0x1eb/0x6d0
[  168.017346]  remove_tree+0x1eb/0x6d0
[  168.019969]  remove_tree+0x1eb/0x6d0
[  168.022128]  qtree_release_dquot+0x291/0x340
[  168.023297]  v2_release_dquot+0xce/0x120
[  168.023847]  dquot_release+0x197/0x3e0
[  168.024358]  ext4_release_dquot+0x22a/0x2d0
[  168.024932]  dqput.part.0+0x1c9/0x900
[  168.025430]  __dquot_drop+0x120/0x190
[  168.025942]  ext4_clear_inode+0x86/0x220
[  168.026472]  ext4_evict_inode+0x9e8/0xa22
[  168.028200]  evict+0x29e/0x4f0
[  168.028625]  dispose_list+0x102/0x1f0
[  168.029148]  evict_inodes+0x2c1/0x3e0
[  168.030188]  generic_shutdown_super+0xa4/0x3b0
[  168.030817]  kill_block_super+0x95/0xd0
[  168.031360]  deactivate_locked_super+0x85/0xd0
[  168.031977]  cleanup_mnt+0x2bc/0x480
[  168.033062]  task_work_run+0xd1/0x170
[  168.033565]  do_exit+0xa4f/0x2b50
[  168.037155]  do_group_exit+0xef/0x2d0
[  168.037666]  __x64_sys_exit_group+0x3a/0x50
[  168.038237]  do_syscall_64+0x3b/0x90
[  168.038751]  entry_SYSCALL_64_after_hwframe+0x44/0xae

In order to reproduce this problem, the following conditions need to be met:
1. Ext4 filesystem with no journal;
2. Filesystem image with incorrect quota data;
3. Abort filesystem forced by user;
4. umount filesystem;

As in ext4_quota_write:
...

         if (EXT4_SB(sb)->s_journal && !handle) {
                 ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
                         " cancelled because transaction is not started",
                         (unsigned long long)off, (unsigned long long)len);
                 return -EIO;
         }
Quoted 3 lines

...
We only check handle if NULL when filesystem has journal. There is need check handle if NULL even when filesystem has no journal.

Quoted 6 lines

Hum, so I think we can just drop this whole condition and warning and instead add a silent return of -EROFS if the filesystem is readonly. That should also fix the bug and also make aborted case less noisy. The message from ext4_quota_write() IMO is not very useful and ext4_bread() will provide us with a BUG and stacktrace which is better for debugging what went wrong anyway.

Quoted 4 lines

Can we really only get here when the fs is read only ? We're going to end up with NULL handle here any time the ext4_journal_start() fails in ext4_release_dquot() which I think can fail for plenty of reasons, not just EROFS.

Hum, that's good point. So probably Ye Bin's patch is as good as it gets :)

Honza

Signature · 2 lines
Jan Kara <[email protected]>
SUSE Labs, CR