Patch "nilfs2: fix missing error check for sb_set_blocksize call" has been added to the 5.4-stable tree

Hi Greg,

Please drop this patch from the 5.4-stable, 4.19-stable, and 4.14-stable queues.

This patch uses nilfs_error() instead of nilfs_err(), which does not yet exist in these versions, but these are different routines and nilfs_error() should not be used as an alternative for init_nilfs(), as it can cause deadlock.

I'll try to post a separate patch to replace it for these versions.

Thanks,
Ryusuke Konishi

Quoted 102 lines · On Sat, Dec 9, 2023 at 9:32 PM wrote:

This is a note to let you know that I've just added the patch titled

nilfs2: fix missing error check for sb_set_blocksize call

to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nilfs2-fix-missing-error-check-for-sb_set_blocksize-call.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From d61d0ab573649789bf9eb909c89a1a193b2e3d10 Mon Sep 17 00:00:00 2001
From: Ryusuke Konishi <[email protected]>
Date: Wed, 29 Nov 2023 23:15:47 +0900
Subject: nilfs2: fix missing error check for sb_set_blocksize call

From: Ryusuke Konishi <[email protected]>

commit d61d0ab573649789bf9eb909c89a1a193b2e3d10 upstream.

When mounting a filesystem image with a block size larger than the page size, nilfs2 repeatedly outputs long error messages with stack traces to the kernel log, such as the following:

getblk(): invalid block size 8192 requested
logical block size: 512
...

 Call Trace:
  dump_stack_lvl+0x92/0xd4
  dump_stack+0xd/0x10
  bdev_getblk+0x33a/0x354
  __breadahead+0x11/0x80
  nilfs_search_super_root+0xe2/0x704 [nilfs2]
  load_nilfs+0x72/0x504 [nilfs2]
  nilfs_mount+0x30f/0x518 [nilfs2]
  legacy_get_tree+0x1b/0x40
  vfs_get_tree+0x18/0xc4
  path_mount+0x786/0xa88
  __ia32_sys_mount+0x147/0x1a8
  __do_fast_syscall_32+0x56/0xc8
  do_fast_syscall_32+0x29/0x58
  do_SYSENTER_32+0x15/0x18
  entry_SYSENTER_32+0x98/0xf1
 ...

This overloads the system logger. And to make matters worse, it sometimes crashes the kernel with a memory access violation.

This is because the return value of the sb_set_blocksize() call, which should be checked for errors, is not checked.

The latter issue is due to out-of-buffer memory being accessed based on a large block size that caused sb_set_blocksize() to fail for buffers read with the initial minimum block size that remained unupdated in the super_block structure.

Since nilfs2 mkfs tool does not accept block sizes larger than the system page size, this has been overlooked. However, it is possible to create this situation by intentionally modifying the tool or by passing a filesystem image created on a system with a large page size to a system with a smaller page size and mounting it.

Fix this issue by inserting the expected error handling for the call to sb_set_blocksize().

Link https://lkml.kernel.org/r/[email protected] open here

Signed-off-by Ryusuke Konishi <[email protected]>

Tested-by Ryusuke Konishi <[email protected]>

Cc <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 fs/nilfs2/the_nilfs.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

fs/nilfs2/the_nilfs.c +5 -1

@@ -688,7 +688,11 @@ int init_nilfs(struct the_nilfs *nilfs,
                        goto failed_sbh;
                }
                nilfs_release_super_block(nilfs);
-               sb_set_blocksize(sb, blocksize);
+               if (!sb_set_blocksize(sb, blocksize)) {
+                       nilfs_error(sb, "bad blocksize %d", blocksize);
+                       err = -EINVAL;
+                       goto out;
+               }
 
                err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
                if (err)

Patches currently in stable-queue which might be from [email protected] are

queue-5.4/nilfs2-prevent-warning-in-nilfs_sufile_set_segment_usage.patch queue-5.4/nilfs2-fix-missing-error-check-for-sb_set_blocksize-call.patch

commit d61d0ab573649789bf9eb909c89a1a193b2e3d10 upstream.

When mounting a filesystem image with a block size larger than the page size, nilfs2 repeatedly outputs long error messages with stack traces to the kernel log, such as the following:

getblk(): invalid block size 8192 requested
logical block size: 512
...

 Call Trace:
  dump_stack_lvl+0x92/0xd4
  dump_stack+0xd/0x10
  bdev_getblk+0x33a/0x354
  __breadahead+0x11/0x80
  nilfs_search_super_root+0xe2/0x704 [nilfs2]
  load_nilfs+0x72/0x504 [nilfs2]
  nilfs_mount+0x30f/0x518 [nilfs2]
  legacy_get_tree+0x1b/0x40
  vfs_get_tree+0x18/0xc4
  path_mount+0x786/0xa88
  __ia32_sys_mount+0x147/0x1a8
  __do_fast_syscall_32+0x56/0xc8
  do_fast_syscall_32+0x29/0x58
  do_SYSENTER_32+0x15/0x18
  entry_SYSENTER_32+0x98/0xf1
 ...

This overloads the system logger. And to make matters worse, it sometimes crashes the kernel with a memory access violation.

This is because the return value of the sb_set_blocksize() call, which should be checked for errors, is not checked.

The latter issue is due to out-of-buffer memory being accessed based on a large block size that caused sb_set_blocksize() to fail for buffers read with the initial minimum block size that remained unupdated in the super_block structure.

Since nilfs2 mkfs tool does not accept block sizes larger than the system page size, this has been overlooked. However, it is possible to create this situation by intentionally modifying the tool or by passing a filesystem image created on a system with a large page size to a system with a smaller page size and mounting it.

Fix this issue by inserting the expected error handling for the call to sb_set_blocksize().

Link https://lkml.kernel.org/r/[email protected] open here

Signed-off-by Ryusuke Konishi <[email protected]>

Tested-by Ryusuke Konishi <[email protected]>

Cc <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

---
Please apply this patch to the stable trees indicated by the subject line prefix, instead of the patch I asked you to drop earlier.

In this patch, "nilfs_err()" is replaced with its equivalent since it doesn't yet exist in these kernels. With this tweak, this patch is applicable from v4.8 to v5.8. Also this patch has been tested against these three stable trees.