Commit 9967d8ac authored by Raghavendra K T's avatar Raghavendra K T Committed by Jens Axboe

null_blk: Null pointer deference problem in alloc_page_buffers

 If we load the null_blk module with bs=8k we get following oops:
[ 3819.812190] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 3819.812387] IP: [<ffffffff81170aa5>] create_empty_buffers+0x28/0xaf
[ 3819.812527] PGD 219244067 PUD 215a06067 PMD 0
[ 3819.812640] Oops: 0000 [#1] SMP
[ 3819.812772] Modules linked in: null_blk(+)

 Fix that by resetting block size to PAGE_SIZE if it is greater than PAGE_SIZE
Reported-by: default avatarSumanth <sumantk2@linux.vnet.ibm.com>
Signed-off-by: default avatarRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: default avatarMatias Bjorling <m@bjorling.me>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 26d58057
...@@ -622,6 +622,11 @@ static int __init null_init(void) ...@@ -622,6 +622,11 @@ static int __init null_init(void)
irqmode = NULL_IRQ_NONE; irqmode = NULL_IRQ_NONE;
} }
#endif #endif
if (bs > PAGE_SIZE) {
pr_warn("null_blk: invalid block size\n");
pr_warn("null_blk: defaults block size to %lu\n", PAGE_SIZE);
bs = PAGE_SIZE;
}
if (queue_mode == NULL_Q_MQ && use_per_node_hctx) { if (queue_mode == NULL_Q_MQ && use_per_node_hctx) {
if (submit_queues < nr_online_nodes) { if (submit_queues < nr_online_nodes) {
......
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