block: tolerate tracing of NULL bio

PATCH Applied Greg Thelen 4 participants 4 messages Sep 8, 2017

Subsystems (2)

Block layer Tracing

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Greg Thelen

author

2017-09-08 00:36 UTC #0 lore raw

PATCH 1/1 block: tolerate tracing of NULL bio

__get_request() can call trace_block_getrq() with bio=NULL which causes block_get_rq::TP_fast_assign() to deref a NULL pointer and panic.

Syzkaller fuzzer panics with
linux-next (1d53d908b79d7870d89063062584eead4cf83448):
kasan: GPF could be caused by NULL-ptr deref or user memory access

  general protection fault: 0000 [#1] SMP KASAN
  Modules linked in:
  CPU: 0 PID: 2983 Comm: syzkaller401111 Not tainted 4.13.0-rc7-next-20170901+ #13
  task: ffff8801cf1da000 task.stack: ffff8801ce440000
  RIP: 0010:perf_trace_block_get_rq+0x697/0x970 include/trace/events/block.h:384
  RSP: 0018:ffff8801ce4473f0 EFLAGS: 00010246
  RAX: ffff8801cf1da000 RBX: 1ffff10039c88e84 RCX: 1ffffd1ffff84d27
  RDX: dffffc0000000001 RSI: 1ffff1003b643e7a RDI: ffffe8ffffc26938
  RBP: ffff8801ce447530 R08: 1ffff1003b643e6c R09: ffffe8ffffc26964
  R10: 0000000000000002 R11: fffff91ffff84d2d R12: ffffe8ffffc1f890
  R13: ffffe8ffffc26930 R14: ffffffff85cad9e0 R15: 0000000000000000
  FS:  0000000002641880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000000000043e670 CR3: 00000001d1d7a000 CR4: 00000000001406f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
    trace_block_getrq include/trace/events/block.h:423 [inline]
    __get_request block/blk-core.c:1283 [inline]
    get_request+0x1518/0x23b0 block/blk-core.c:1355
    blk_old_get_request block/blk-core.c:1402 [inline]
    blk_get_request+0x1d8/0x3c0 block/blk-core.c:1427
    sg_scsi_ioctl+0x117/0x750 block/scsi_ioctl.c:451
    sg_ioctl+0x192d/0x2ed0 drivers/scsi/sg.c:1070
    vfs_ioctl fs/ioctl.c:45 [inline]
    do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
    SYSC_ioctl fs/ioctl.c:700 [inline]
    SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
    entry_SYSCALL_64_fastpath+0x1f/0xbe

block_get_rq::TP_fast_assign() has multiple redundant ->dev assignments. Only one of them is NULL tolerant. Favor the NULL tolerant one.

Fixes 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and partitions index")

Signed-off-by Greg Thelen <[email protected]>

---
 include/trace/events/block.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

include/trace/events/block.h +2 -3

index f815aaaef755..1fd7ff1a46f7 100644
@@ -397,7 +397,6 @@ DECLARE_EVENT_CLASS(block_get_rq,
 
 	TP_fast_assign(
 		__entry->dev		= bio ? bio_dev(bio) : 0;
-		__entry->dev		= bio_dev(bio);
 		__entry->sector		= bio ? bio->bi_iter.bi_sector : 0;
 		__entry->nr_sector	= bio ? bio_sectors(bio) : 0;
 		blk_fill_rwbs(__entry->rwbs,

@@ -414,7 +413,7 @@ DECLARE_EVENT_CLASS(block_get_rq,
 /**
  * block_getrq - get a free request entry in queue for block IO operations
  * @q: queue for operations
- * @bio: pending block IO operation
+ * @bio: pending block IO operation (can be %NULL)
  * @rw: low bit indicates a read (%0) or a write (%1)
  *
  * A request struct for queue @q has been allocated to handle the

@@ -430,7 +429,7 @@ DEFINE_EVENT(block_get_rq, block_getrq,
 /**
  * block_sleeprq - waiting to get a free request entry in queue for block IO operation
  * @q: queue for operation
- * @bio: pending block IO operation
+ * @bio: pending block IO operation (can be %NULL)
  * @rw: low bit indicates a read (%0) or a write (%1)
  *
  * In the case where a request struct cannot be provided for queue @q

Signature · 1 line

2.14.1.581.gf28d330327-goog

Ming Lei

Reviewed-by on v1 1/1

2017-09-08 01:24 UTC #1 lore raw

Quoted 76 lines · Greg Thelen

__get_request() can call trace_block_getrq() with bio=NULL which causes block_get_rq::TP_fast_assign() to deref a NULL pointer and panic.

Syzkaller fuzzer panics with
linux-next (1d53d908b79d7870d89063062584eead4cf83448):
kasan: GPF could be caused by NULL-ptr deref or user memory access

  general protection fault: 0000 [#1] SMP KASAN
  Modules linked in:
  CPU: 0 PID: 2983 Comm: syzkaller401111 Not tainted 4.13.0-rc7-next-20170901+ #13
  task: ffff8801cf1da000 task.stack: ffff8801ce440000
  RIP: 0010:perf_trace_block_get_rq+0x697/0x970 include/trace/events/block.h:384
  RSP: 0018:ffff8801ce4473f0 EFLAGS: 00010246
  RAX: ffff8801cf1da000 RBX: 1ffff10039c88e84 RCX: 1ffffd1ffff84d27
  RDX: dffffc0000000001 RSI: 1ffff1003b643e7a RDI: ffffe8ffffc26938
  RBP: ffff8801ce447530 R08: 1ffff1003b643e6c R09: ffffe8ffffc26964
  R10: 0000000000000002 R11: fffff91ffff84d2d R12: ffffe8ffffc1f890
  R13: ffffe8ffffc26930 R14: ffffffff85cad9e0 R15: 0000000000000000
  FS:  0000000002641880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000000000043e670 CR3: 00000001d1d7a000 CR4: 00000000001406f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
    trace_block_getrq include/trace/events/block.h:423 [inline]
    __get_request block/blk-core.c:1283 [inline]
    get_request+0x1518/0x23b0 block/blk-core.c:1355
    blk_old_get_request block/blk-core.c:1402 [inline]
    blk_get_request+0x1d8/0x3c0 block/blk-core.c:1427
    sg_scsi_ioctl+0x117/0x750 block/scsi_ioctl.c:451
    sg_ioctl+0x192d/0x2ed0 drivers/scsi/sg.c:1070
    vfs_ioctl fs/ioctl.c:45 [inline]
    do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
    SYSC_ioctl fs/ioctl.c:700 [inline]
    SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
    entry_SYSCALL_64_fastpath+0x1f/0xbe

block_get_rq::TP_fast_assign() has multiple redundant ->dev assignments. Only one of them is NULL tolerant. Favor the NULL tolerant one.

Fixes 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and partitions index")

Signed-off-by Greg Thelen <[email protected]>

---
 include/trace/events/block.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

include/trace/events/block.h +2 -4

index f815aaaef755..1fd7ff1a46f7 100644
@@ -397,7 +397,6 @@ DECLARE_EVENT_CLASS(block_get_rq,
 
        TP_fast_assign(
                __entry->dev            = bio ? bio_dev(bio) : 0;
-               __entry->dev            = bio_dev(bio);
                __entry->sector         = bio ? bio->bi_iter.bi_sector : 0;
                __entry->nr_sector      = bio ? bio_sectors(bio) : 0;
                blk_fill_rwbs(__entry->rwbs,

@@ -414,7 +413,7 @@ DECLARE_EVENT_CLASS(block_get_rq,
 /**
  * block_getrq - get a free request entry in queue for block IO operations
  * @q: queue for operations
- * @bio: pending block IO operation
+ * @bio: pending block IO operation (can be %NULL)
  * @rw: low bit indicates a read (%0) or a write (%1)
  *
  * A request struct for queue @q has been allocated to handle the

@@ -430,7 +429,7 @@ DEFINE_EVENT(block_get_rq, block_getrq,
 /**
  * block_sleeprq - waiting to get a free request entry in queue for block IO operation
  * @q: queue for operation
- * @bio: pending block IO operation
+ * @bio: pending block IO operation (can be %NULL)
  * @rw: low bit indicates a read (%0) or a write (%1)
  *
  * In the case where a request struct cannot be provided for queue @q
--

Quoted 2 lines

2.14.1.581.gf28d330327-goog

Reviewed-by Ming Lei <[email protected]>

Signature · 1 line

Ming Lei

Christoph Hellwig

Reviewed-by on v1 1/1

2017-09-08 08:12 UTC #2 lore raw

In reply to Greg Thelen

Looks good,

Reviewed-by Christoph Hellwig <[email protected]>

Jens Axboe

maintainer Applied

2017-09-08 14:25 UTC #3 lore raw

In reply to Greg Thelen

Quoted 36 lines · Greg Thelen

__get_request() can call trace_block_getrq() with bio=NULL which causes block_get_rq::TP_fast_assign() to deref a NULL pointer and panic.

Syzkaller fuzzer panics with
linux-next (1d53d908b79d7870d89063062584eead4cf83448):
kasan: GPF could be caused by NULL-ptr deref or user memory access

  general protection fault: 0000 [#1] SMP KASAN
  Modules linked in:
  CPU: 0 PID: 2983 Comm: syzkaller401111 Not tainted 4.13.0-rc7-next-20170901+ #13
  task: ffff8801cf1da000 task.stack: ffff8801ce440000
  RIP: 0010:perf_trace_block_get_rq+0x697/0x970 include/trace/events/block.h:384
  RSP: 0018:ffff8801ce4473f0 EFLAGS: 00010246
  RAX: ffff8801cf1da000 RBX: 1ffff10039c88e84 RCX: 1ffffd1ffff84d27
  RDX: dffffc0000000001 RSI: 1ffff1003b643e7a RDI: ffffe8ffffc26938
  RBP: ffff8801ce447530 R08: 1ffff1003b643e6c R09: ffffe8ffffc26964
  R10: 0000000000000002 R11: fffff91ffff84d2d R12: ffffe8ffffc1f890
  R13: ffffe8ffffc26930 R14: ffffffff85cad9e0 R15: 0000000000000000
  FS:  0000000002641880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000000000043e670 CR3: 00000001d1d7a000 CR4: 00000000001406f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
    trace_block_getrq include/trace/events/block.h:423 [inline]
    __get_request block/blk-core.c:1283 [inline]
    get_request+0x1518/0x23b0 block/blk-core.c:1355
    blk_old_get_request block/blk-core.c:1402 [inline]
    blk_get_request+0x1d8/0x3c0 block/blk-core.c:1427
    sg_scsi_ioctl+0x117/0x750 block/scsi_ioctl.c:451
    sg_ioctl+0x192d/0x2ed0 drivers/scsi/sg.c:1070
    vfs_ioctl fs/ioctl.c:45 [inline]
    do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
    SYSC_ioctl fs/ioctl.c:700 [inline]
    SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
    entry_SYSCALL_64_fastpath+0x1f/0xbe

Quoted 2 lines

block_get_rq::TP_fast_assign() has multiple redundant ->dev assignments. Only one of them is NULL tolerant. Favor the NULL tolerant one.

Applied, thanks.

Signature · 1 line

Jens Axboe