From: Roland Dreier Date: Mon, 16 Jul 2012 22:34:24 +0000 (-0700) Subject: target: Fix possible integer underflow in UNMAP emulation X-Git-Tag: v3.2.25~30 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=76191bb22af0d68261d5d9a9b6294d68133813e0;p=thirdparty%2Fkernel%2Fstable.git target: Fix possible integer underflow in UNMAP emulation commit b7fc7f3777582dea85156a821d78a522a0c083aa upstream. It's possible for an initiator to send us an UNMAP command with a descriptor that is less than 8 bytes; in that case it's really bad for us to set an unsigned int to that value, subtract 8 from it, and then use that as a limit for our loop (since the value will wrap around to a huge positive value). Fix this by making size be signed and only looping if size >= 16 (ie if we have at least a full descriptor available). Also remove offset as an obfuscated name for the constant 8. Signed-off-by: Roland Dreier Signed-off-by: Nicholas Bellinger [bwh: Backported to 3.2: adjust filename, context] Signed-off-by: Ben Hutchings --- diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c index b1f5cf010a296..00f0f7dc9dcf6 100644 --- a/drivers/target/target_core_cdb.c +++ b/drivers/target/target_core_cdb.c @@ -1115,9 +1115,10 @@ int target_emulate_unmap(struct se_task *task) struct se_device *dev = cmd->se_dev; unsigned char *buf, *ptr = NULL; sector_t lba; - unsigned int size = cmd->data_length, range; - int ret = 0, offset; - unsigned short dl, bd_dl; + int size = cmd->data_length; + u32 range; + int ret = 0; + int dl, bd_dl; if (!dev->transport->do_discard) { pr_err("UNMAP emulation not supported for: %s\n", @@ -1126,20 +1127,19 @@ int target_emulate_unmap(struct se_task *task) return -ENOSYS; } - /* First UNMAP block descriptor starts at 8 byte offset */ - offset = 8; - size -= 8; - buf = transport_kmap_data_sg(cmd); dl = get_unaligned_be16(&buf[0]); bd_dl = get_unaligned_be16(&buf[2]); - ptr = &buf[offset]; - pr_debug("UNMAP: Sub: %s Using dl: %hu bd_dl: %hu size: %hu" + size = min(size - 8, bd_dl); + + /* First UNMAP block descriptor starts at 8 byte offset */ + ptr = &buf[8]; + pr_debug("UNMAP: Sub: %s Using dl: %u bd_dl: %u size: %u" " ptr: %p\n", dev->transport->name, dl, bd_dl, size, ptr); - while (size) { + while (size >= 16) { lba = get_unaligned_be64(&ptr[0]); range = get_unaligned_be32(&ptr[8]); pr_debug("UNMAP: Using lba: %llu and range: %u\n",