[BUG]
With kmalloc failure injection for submit_one_bio(), btrfs can crash like:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
#PF error: [WRITE]
PGD 0 P4D 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 1 PID: 247 Comm: kworker/u8:4 Not tainted 5.1.0-rc5-custom+ #19
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Workqueue: writeback wb_workfn (flush-btrfs-6)
RIP: 0010:alloc_btrfs_bio+0x1e/0x30 [btrfs]
Call Trace:
__btrfs_map_block+0x5ce/0x1210 [btrfs]
? btrfs_bio_counter_inc_blocked+0x3a/0xc0 [btrfs]
btrfs_map_bio+0x9a/0x430 [btrfs]
btree_submit_bio_hook+0x82/0xb0 [btrfs]
submit_one_bio+0x95/0xc0 [btrfs]
copy_oldmem_page_encrypted+0x20/0x20
? write_one_eb+0x18f/0x2a0 [btrfs]
? end_extent_buffer_writeback+0x20/0x20 [btrfs]
? btree_write_cache_pages+0x12c/0x350 [btrfs]
? do_writepages+0x41/0xd0
? __writeback_single_inode+0x54/0x650
? writeback_sb_inodes+0x1f9/0x540
? __writeback_inodes_wb+0x5d/0xb0
? wb_writeback+0x340/0x4b0
? wb_workfn+0x410/0x5d0
? process_one_work+0x294/0x650
? worker_thread+0x2d/0x3d0
? process_one_work+0x650/0x650
? kthread+0x112/0x130
? kthread_park+0x80/0x80
? ret_from_fork+0x3a/0x50
---[ end trace b637169fb8b17c9c ]---
[CAUSE]
The kmalloc() call in alloc_btrfs_bio() has __GFP_NOFAIL flag set, so we
don't check the returned pointer.
However all alloc_btrfs_bio() callers have checked NULL pointer, thus
even we kmalloc() failed, we won't panic anyway.
[FIX]
Remove the __GFP_NOFAIL flag and check the returned pointer from
kmalloc().
Signed-off-by: Qu Wenruo <w...@suse.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
---
Changelog:
- Remove the __GFP_NOFAIL flag
Especially when all callers are handling memory allocation failure,
there is no need for __GFP_NOFAIL.
---
fs/btrfs/volumes.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 78bab7803bda..7e1ad6dd672e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5580,8 +5580,10 @@ static struct btrfs_bio *alloc_btrfs_bio(int
total_stripes, int real_stripes)
* and the stripes
*/
sizeof(u64) * (total_stripes),
- GFP_NOFS|__GFP_NOFAIL);
+ GFP_NOFS);
+ if (!bbio)
+ return NULL;
atomic_set(&bbio->error, 0);
refcount_set(&bbio->refs, 1);
--
2.21.0
