From eb81b328267b2d97d11441483f5ac9dccb505818 Mon Sep 17 00:00:00 2001
From: Guoqing Jiang <gqjiang@suse.com>
Date: Thu, 26 Apr 2018 10:56:37 +0800
Subject: [PATCH] raid10: check bio in r10buf_pool_free to void NULL pointer
dereference
Git-commit: eb81b328267b2d97d11441483f5ac9dccb505818
Patch-mainline: v4.18-rc1
References: bsc#1098174
For recovery case, r10buf_pool_alloc only allocates 2 bios,
so we can't access more than 2 bios in r10buf_pool_free.
Otherwise, we can see NULL pointer dereference as follows:
[ 98.347009] BUG: unable to handle kernel NULL pointer dereference
at 0000000000000050
[ 98.355783] IP: r10buf_pool_free+0x38/0xe0 [raid10]
[...]
[ 98.543734] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 98.550161] CR2: 0000000000000050 CR3: 000000089500a001 CR4: 00000000001606f0
[ 98.558145] Call Trace:
[ 98.560881] <IRQ>
[ 98.563136] put_buf+0x19/0x20 [raid10]
[ 98.567426] end_sync_request+0x6b/0x70 [raid10]
[ 98.572591] end_sync_write+0x9b/0x160 [raid10]
[ 98.577662] blk_update_request+0x78/0x2c0
[ 98.582254] scsi_end_request+0x2c/0x1e0 [scsi_mod]
[ 98.587719] scsi_io_completion+0x22f/0x610 [scsi_mod]
[ 98.593472] blk_done_softirq+0x8e/0xc0
[ 98.597767] __do_softirq+0xde/0x2b3
[ 98.601770] irq_exit+0xae/0xb0
[ 98.605285] do_IRQ+0x81/0xd0
[ 98.608606] common_interrupt+0x7d/0x7d
[ 98.612898] </IRQ>
So we need to check the bio is valid or not before the bio is
used in r10buf_pool_free. Another workable way is to free 2 bios
for recovery case just like r10buf_pool_alloc.
Fixes: f0250618361d ("md: raid10: don't use bio's vec table to manage resync pages")
Reported-by: Alexis Castilla <pencerval@gmail.com>
Tested-by: Alexis Castilla <pencerval@gmail.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Guoqing Jiang <gqjiang@suse.com>
---
drivers/md/raid10.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 64300542ab20..976ef8cae64c 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -255,9 +255,11 @@ static void r10buf_pool_free(void *__r10_bio, void *data)
for (j = conf->copies; j--; ) {
struct bio *bio = r10bio->devs[j].bio;
- rp = get_resync_pages(bio);
- resync_free_pages(rp);
- bio_put(bio);
+ if (bio) {
+ rp = get_resync_pages(bio);
+ resync_free_pages(rp);
+ bio_put(bio);
+ }
bio = r10bio->devs[j].repl_bio;
if (bio)
--
2.13.1