Messages in this thread | | | From | Konrad Rzeszutek Wilk <> | Subject | [PATCH] fixes to xen-blk[back|front] to deal with 32/64 host/guest combination with BLKIF_DISCARD (v1). | Date | Fri, 25 May 2012 17:50:01 -0400 |
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These two patches came out of hitting https://bugzilla.redhat.com/show_bug.cgi?id=824641 where a 32-bit guest would send a BLKIF_DISCARD request to a 64-bit host. The xen-blkback did not copy the 'id' field into the response (it ended up with a random value), which the frontend uses to lookup in its array to find the 'struct request' that corresponded to this BLKIF_DISCARD.
The result was the __blk_end_request_all ended being called with a NULL pointer and crashed the guest.
The fix is easy enough - make xen-blkback copy the 'id' field when dealing with 32/64 or 64/32 host/guest combinations. The problem does not exist if we are using a 64/64 combination.
I also added two BUG_ON to xen-blkfront to detect this misuse of 'id' field in case there are other backends that do this.
If there are no problems with these patches I was thinking to put them in my stable/for-jens-3.5 tree and ask Jens to pull them.
drivers/block/xen-blkback/common.h | 2 ++ drivers/block/xen-blkfront.c | 7 +++++++ 2 files changed, 9 insertions(+), 0 deletions(-)
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