| Message ID | 1450214683-14062-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c index 384f20c..973fd98 100644 --- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -487,11 +487,11 @@ static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool succes if (block_size < PAGE_SIZE) { sg_set_page(&write_sg[i], m.page, block_size, - block_size); + m.piter.sg->offset + block_size); } else { sg_miter_next(&m); sg_set_page(&write_sg[i], m.page, block_size, - 0); + m.piter.sg->offset); } len -= block_size; i++;
This is a note to let you know that I have just added a patch titled target: fix COMPARE_AND_WRITE non zero SGL offset data corruption to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 277c2147f3f59f0425136651928a053826d54a64 Mon Sep 17 00:00:00 2001 From: Jan Engelhardt <jengelh@inai.de> Date: Mon, 23 Nov 2015 17:46:32 +0100 Subject: target: fix COMPARE_AND_WRITE non zero SGL offset data corruption commit d94e5a61357a04938ce14d6033b4d33a3c5fd780 upstream. target_core_sbc's compare_and_write functionality suffers from taking data at the wrong memory location when writing a CAW request to disk when a SGL offset is non-zero. This can happen with loopback and vhost-scsi fabric drivers when SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC is used to map existing user-space SGL memory into COMPARE_AND_WRITE READ/WRITE payload buffers. Given the following sample LIO subtopology, % targetcli ls /loopback/ o- loopback ................................. [1 Target] o- naa.6001405ebb8df14a ....... [naa.60014059143ed2b3] o- luns ................................... [2 LUNs] o- lun0 ................ [iblock/ram0 (/dev/ram0)] o- lun1 ................ [iblock/ram1 (/dev/ram1)] % lsscsi -g [3:0:1:0] disk LIO-ORG IBLOCK 4.0 /dev/sdc /dev/sg3 [3:0:1:1] disk LIO-ORG IBLOCK 4.0 /dev/sdd /dev/sg4 the following bug can be observed in Linux 4.3 and 4.4~rc1: % perl -e 'print chr$_ for 0..255,reverse 0..255' >rand % perl -e 'print "\0" x 512' >zero % cat rand >/dev/sdd % sg_compare_and_write -i rand -D zero --lba 0 /dev/sdd % sg_compare_and_write -i zero -D rand --lba 0 /dev/sdd Miscompare reported % hexdump -Cn 512 /dev/sdd 00000000 0f 0e 0d 0c 0b 0a 09 08 07 06 05 04 03 02 01 00 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 00000200 Rather than writing all-zeroes as instructed with the -D file, it corrupts the data in the sector by splicing some of the original bytes in. The page of the first entry of cmd->t_data_sg includes the CDB, and sg->offset is set to a position past the CDB. I presume that sg->offset is also the right choice to use for subsequent sglist members. Signed-off-by: Jan Engelhardt <jengelh@netitwork.de> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/target/target_core_sbc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 1.9.1