From 8c9ce606a60e4a0cb447bdc082ce383b96b227b4 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Fri, 25 May 2012 16:11:09 -0400 Subject: [PATCH 2/3] xen/blkback: Copy id field when doing BLKIF_DISCARD. We weren't copying the id field so when we sent the response back to the frontend (especially with a 64-bit host and 32-bit guest), we ended up using a random value. This lead to the frontend crashing as it would try to pass to __blk_end_request_all a NULL 'struct request' (b/c it would use the 'id' to find the proper 'struct request' in its shadow array) and end up crashing: BUG: unable to handle kernel NULL pointer dereference at 000000e4 IP: [] __blk_end_request_all+0xc/0x40 .. snip.. EIP is at __blk_end_request_all+0xc/0x40 .. snip.. [] blkif_interrupt+0x172/0x330 [xen_blkfront] This fixes the bug by passing in the proper id for the response. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=824641 CC: stable@kernel.org Tested-by: William Dauchy Acked-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk --- drivers/block/xen-blkback/common.h | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index 773cf27..9ad3b5e 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -257,6 +257,7 @@ static inline void blkif_get_x86_32_req(struct blkif_request *dst, break; case BLKIF_OP_DISCARD: dst->u.discard.flag = src->u.discard.flag; + dst->u.discard.id = src->u.discard.id; dst->u.discard.sector_number = src->u.discard.sector_number; dst->u.discard.nr_sectors = src->u.discard.nr_sectors; break; @@ -287,6 +288,7 @@ static inline void blkif_get_x86_64_req(struct blkif_request *dst, break; case BLKIF_OP_DISCARD: dst->u.discard.flag = src->u.discard.flag; + dst->u.discard.id = src->u.discard.id; dst->u.discard.sector_number = src->u.discard.sector_number; dst->u.discard.nr_sectors = src->u.discard.nr_sectors; break; -- 1.7.4.4