From: Ye Bin <yebin10@xxxxxxxxxx> [ Upstream commit f347c26836c270199de1599c3cd466bb7747caa9 ] The following issue was observed running syzkaller: BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:377 [inline] BUG: KASAN: slab-out-of-bounds in sg_copy_buffer+0x150/0x1c0 lib/scatterlist.c:831 Read of size 2132 at addr ffff8880aea95dc8 by task syz-executor.0/9815 CPU: 0 PID: 9815 Comm: syz-executor.0 Not tainted 4.19.202-00874-gfc0fe04215a9 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xe4/0x14a lib/dump_stack.c:118 print_address_description+0x73/0x280 mm/kasan/report.c:253 kasan_report_error mm/kasan/report.c:352 [inline] kasan_report+0x272/0x370 mm/kasan/report.c:410 memcpy+0x1f/0x50 mm/kasan/kasan.c:302 memcpy include/linux/string.h:377 [inline] sg_copy_buffer+0x150/0x1c0 lib/scatterlist.c:831 fill_from_dev_buffer+0x14f/0x340 drivers/scsi/scsi_debug.c:1021 resp_report_tgtpgs+0x5aa/0x770 drivers/scsi/scsi_debug.c:1772 schedule_resp+0x464/0x12f0 drivers/scsi/scsi_debug.c:4429 scsi_debug_queuecommand+0x467/0x1390 drivers/scsi/scsi_debug.c:5835 scsi_dispatch_cmd+0x3fc/0x9b0 drivers/scsi/scsi_lib.c:1896 scsi_request_fn+0x1042/0x1810 drivers/scsi/scsi_lib.c:2034 __blk_run_queue_uncond block/blk-core.c:464 [inline] __blk_run_queue+0x1a4/0x380 block/blk-core.c:484 blk_execute_rq_nowait+0x1c2/0x2d0 block/blk-exec.c:78 sg_common_write.isra.19+0xd74/0x1dc0 drivers/scsi/sg.c:847 sg_write.part.23+0x6e0/0xd00 drivers/scsi/sg.c:716 sg_write+0x64/0xa0 drivers/scsi/sg.c:622 __vfs_write+0xed/0x690 fs/read_write.c:485 kill_bdev:block_device:00000000e138492c vfs_write+0x184/0x4c0 fs/read_write.c:549 ksys_write+0x107/0x240 fs/read_write.c:599 do_syscall_64+0xc2/0x560 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe We get 'alen' from command its type is int. If userspace passes a large length we will get a negative 'alen'. Switch n, alen, and rlen to u32. Link: https://lore.kernel.org/r/20211013033913.2551004-3-yebin10@xxxxxxxxxx Acked-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/scsi/scsi_debug.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c index 63504dc63d878..3fc7c2a31c191 100644 --- a/drivers/scsi/scsi_debug.c +++ b/drivers/scsi/scsi_debug.c @@ -1895,8 +1895,9 @@ static int resp_report_tgtpgs(struct scsi_cmnd *scp, unsigned char *cmd = scp->cmnd; unsigned char *arr; int host_no = devip->sdbg_host->shost->host_no; - int n, ret, alen, rlen; int port_group_a, port_group_b, port_a, port_b; + u32 alen, n, rlen; + int ret; alen = get_unaligned_be32(cmd + 6); arr = kzalloc(SDEBUG_MAX_TGTPGS_ARR_SZ, GFP_ATOMIC); @@ -1958,9 +1959,9 @@ static int resp_report_tgtpgs(struct scsi_cmnd *scp, * - The constructed command length * - The maximum array size */ - rlen = min_t(int, alen, n); + rlen = min(alen, n); ret = fill_from_dev_buffer(scp, arr, - min_t(int, rlen, SDEBUG_MAX_TGTPGS_ARR_SZ)); + min_t(u32, rlen, SDEBUG_MAX_TGTPGS_ARR_SZ)); kfree(arr); return ret; } -- 2.33.0
