lkml.org 
[lkml]   [2014]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC PATCH V3 1/2] null_blk: Null pointer deference problem in alloc_page_buffers
    Date

    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: Sumanth <sumantk2@linux.vnet.ibm.com>
    Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
    ---
    drivers/block/null_blk.c | 5 +++++
    1 file changed, 5 insertions(+)

    diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
    index a2e69d2..a01d7f6 100644
    --- a/drivers/block/null_blk.c
    +++ b/drivers/block/null_blk.c
    @@ -622,6 +622,11 @@ static int __init null_init(void)
    irqmode = NULL_IRQ_NONE;
    }
    #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 (submit_queues < nr_online_nodes) {
    --
    1.7.11.7


    \
     
     \ /
      Last update: 2014-01-21 13:21    [W:2.734 / U:0.160 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site