4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bryant G Ly bryantly@linux.vnet.ibm.com
commit f5957dade4f373b04fa1f5315a489f18cc2c4cb4 upstream.
memcmp() requires the two buffers passed as arguments to be at least 'size' bytes long, otherwise a fortify_panic will trigger.
Use memchr_inv() instead of memcmp() to determine whether the received payload is zeroed or not.
The bug was found by running a block backstore via LIO.
[ 496.212958] Call Trace: [ 496.212960] [c0000007e58e3800] [c000000000cbbefc] fortify_panic+0x24/0x38 (unreliable) [ 496.212965] [c0000007e58e3860] [d00000000f150c28] iblock_execute_write_same+0x3b8/0x3c0 [target_core_iblock] [ 496.212976] [c0000007e58e3910] [d000000006c737d4] __target_execute_cmd+0x54/0x150 [target_core_mod] [ 496.212982] [c0000007e58e3940] [d000000006d32ce4] ibmvscsis_write_pending+0x74/0xe0 [ibmvscsis] [ 496.212991] [c0000007e58e39b0] [d000000006c74fc8] transport_generic_new_cmd+0x318/0x370 [target_core_mod] [ 496.213001] [c0000007e58e3a30] [d000000006c75084] transport_handle_cdb_direct+0x64/0xd0 [target_core_mod] [ 496.213011] [c0000007e58e3aa0] [d000000006c75298] target_submit_cmd_map_sgls+0x1a8/0x320 [target_core_mod] [ 496.213021] [c0000007e58e3b30] [d000000006c75458] target_submit_cmd+0x48/0x60 [target_core_mod] [ 496.213026] [c0000007e58e3bd0] [d000000006d34c20] ibmvscsis_scheduler+0x370/0x600 [ibmvscsis] [ 496.213031] [c0000007e58e3c90] [c00000000013135c] process_one_work+0x1ec/0x580 [ 496.213035] [c0000007e58e3d20] [c000000000131798] worker_thread+0xa8/0x600 [ 496.213039] [c0000007e58e3dc0] [c00000000013a468] kthread+0x168/0x1b0 [ 496.213044] [c0000007e58e3e30] [c00000000000b528] ret_from_kernel_thread+0x5c/0xb4
[mkp: tweaked commit message]
Fixes: 2237498f0b5c ("target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout") Signed-off-by: Bryant G. Ly bryantly@linux.vnet.ibm.com Reviewed-by: Steven Royer seroyer@linux.vnet.ibm.com Tested-by: Taylor Jakobson tjakobs@us.ibm.com Cc: Christoph Hellwig hch@lst.de Cc: Nicholas Bellinger nab@linux-iscsi.org Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/target/target_core_iblock.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/target/target_core_iblock.c +++ b/drivers/target/target_core_iblock.c @@ -427,8 +427,8 @@ iblock_execute_zero_out(struct block_dev { struct se_device *dev = cmd->se_dev; struct scatterlist *sg = &cmd->t_data_sg[0]; - unsigned char *buf, zero = 0x00, *p = &zero; - int rc, ret; + unsigned char *buf, *not_zero; + int ret;
buf = kmap(sg_page(sg)) + sg->offset; if (!buf) @@ -437,10 +437,10 @@ iblock_execute_zero_out(struct block_dev * Fall back to block_execute_write_same() slow-path if * incoming WRITE_SAME payload does not contain zeros. */ - rc = memcmp(buf, p, cmd->data_length); + not_zero = memchr_inv(buf, 0x00, cmd->data_length); kunmap(sg_page(sg));
- if (rc) + if (not_zero) return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
ret = blkdev_issue_zeroout(bdev,