From eb81b328267b2d97d11441483f5ac9dccb505818 Mon Sep 17 00:00:00 2001 From: Guoqing Jiang Date: Thu, 26 Apr 2018 10:56:37 +0800 Subject: raid10: check bio in r10buf_pool_free to void NULL pointer dereference 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] [ 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] 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 Tested-by: Alexis Castilla Signed-off-by: Guoqing Jiang Signed-off-by: Shaohua Li --- drivers/md/raid10.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'drivers/md/raid10.c') 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) -- cgit v1.2.3