[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]
Code: 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 0f 1f 44 00 00 48 63 f6 48 63 ff 48
8d 7c fe 18 be 40 8d 00 00 48 c1 e7 02 e8 a2 86 94 e0 <c7> 40 38 00 00 00 00 c7
00 01 00 00 00 c3 0f 1f 40 00 0f 1f 44 00
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]
We just forgot to check the return value of kmalloc.
Surprisingly, all alloc_btrfs_bio() callers have handled memory
allocation pretty well.
[FIX]
Check and return if we failed memory allocation.
Signed-off-by: Qu Wenruo <w...@suse.com>
---
fs/btrfs/volumes.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 78bab7803bda..875d0eee1785 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5582,6 +5582,8 @@ static struct btrfs_bio *alloc_btrfs_bio(int
total_stripes, int real_stripes)
sizeof(u64) * (total_stripes),
GFP_NOFS|__GFP_NOFAIL);
+ if (!bbio)
+ return NULL;
atomic_set(&bbio->error, 0);
refcount_set(&bbio->refs, 1);
--
2.21.0
