cifs: Allocate validate negotiation request through kmalloc

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commit 2796d303e3 upstream.

The data buffer allocated on the stack can't be DMA'ed, ib_dma_map_page will
return an invalid DMA address for a buffer on stack. Even worse, this
incorrect address can't be detected by ib_dma_mapping_error. Sending data
from this address to hardware will not fail, but the remote peer will get
junk data.

Fix this by allocating the request on the heap in smb3_validate_negotiate.

Changes in v2:
Removed duplicated code on freeing buffers on function exit.
(Thanks to Parav Pandit <parav@mellanox.com>)
Fixed typo in the patch title.

Changes in v3:
Added "Fixes" to the patch.
Changed several sizeof() to use *pointer in place of struct.

Changes in v4:
Added detailed comments on the failure through RDMA.
Allocate request buffer using GPF_NOFS.
Fixed possible memory leak.

Changes in v5:
Removed variable ret for checking return value.
Changed to use pneg_inbuf->Dialects[0] to calculate unused space in pneg_inbuf.

Fixes: ff1c038add ("Check SMB3 dialects against downgrade attacks")
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Tom Talpey <ttalpey@microsoft.com>
[bwh: Backported to 3.16: We only ever pass one dialect]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

This commit is contained in:

Long Li 2018-04-25 11:30:04 -07:00 • committed by Ben Hutchings

parent dd928eae0c

commit 17aa2271b2

1 changed files with 26 additions and 19 deletions

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fs/cifs/smb2pdu.c

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