* [PATCH] scsi: target: iscsi: reject zero-length Extended CDB AHS
@ 2026-04-04 1:44 carlos.bilbao
2026-04-07 9:23 ` Dmitry Bogdanov
2026-04-09 2:42 ` [PATCH v2] scsi: target: iscsi: reject invalid size " carlos.bilbao
0 siblings, 2 replies; 5+ messages in thread
From: carlos.bilbao @ 2026-04-04 1:44 UTC (permalink / raw)
To: martin.petersen, kees
Cc: pabeni, mlombard, kuniyu, d.bogdanov, michael.christie,
linux-scsi, target-devel, linux-kernel, bilbao, Carlos Bilbao
From: Carlos Bilbao <carlos.bilbao@kernel.org>
If ecdb_ahdr->ahslength is zero, two bugs follow:
kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15, ...)
allocates 15 bytes, but the immediately following memcpy writes
ISCSI_CDB_SIZE (16) bytes into it, a one-byte heap overflow. Also:
memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
be16_to_cpu(ecdb_ahdr->ahslength) - 1);
(u16)0 - 1 promotes to (int)-1 which converts to SIZE_MAX as size_t,
causing a massive out-of-bounds write.
Reject ahslength == 0 with ISCSI_REASON_PROTOCOL_ERROR before the kmalloc.
Fixes: 8f1f7d297bce ("scsi: target: iscsi: Add support for extended CDB AHS")
Signed-off-by: Carlos Bilbao (Lambda) <carlos.bilbao@kernel.org>
---
drivers/target/iscsi/iscsi_target.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index e80449f6ce15..8db24d35c762 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1100,6 +1100,8 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
cdb = hdr->cdb;
if (hdr->hlength) {
+ u16 ahslength;
+
ecdb_ahdr = (struct iscsi_ecdb_ahdr *) (hdr + 1);
if (ecdb_ahdr->ahstype != ISCSI_AHSTYPE_CDB) {
pr_err("Additional Header Segment type %d not supported!\n",
@@ -1108,14 +1110,19 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
ISCSI_REASON_CMD_NOT_SUPPORTED, buf);
}
- cdb = kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15,
- GFP_KERNEL);
+ ahslength = be16_to_cpu(ecdb_ahdr->ahslength);
+ if (!ahslength) {
+ pr_err("Extended CDB AHS with zero length, protocol error.\n");
+ return iscsit_add_reject_cmd(cmd,
+ ISCSI_REASON_PROTOCOL_ERROR, buf);
+ }
+
+ cdb = kmalloc(ahslength + 15, GFP_KERNEL);
if (cdb == NULL)
return iscsit_add_reject_cmd(cmd,
ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
- memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
- be16_to_cpu(ecdb_ahdr->ahslength) - 1);
+ memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, ahslength - 1);
}
data_direction = (hdr->flags & ISCSI_FLAG_CMD_WRITE) ? DMA_TO_DEVICE :
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] scsi: target: iscsi: reject zero-length Extended CDB AHS
2026-04-04 1:44 [PATCH] scsi: target: iscsi: reject zero-length Extended CDB AHS carlos.bilbao
@ 2026-04-07 9:23 ` Dmitry Bogdanov
2026-04-09 2:23 ` Carlos Bilbao
2026-04-09 2:42 ` [PATCH v2] scsi: target: iscsi: reject invalid size " carlos.bilbao
1 sibling, 1 reply; 5+ messages in thread
From: Dmitry Bogdanov @ 2026-04-07 9:23 UTC (permalink / raw)
To: carlos.bilbao
Cc: martin.petersen, kees, pabeni, mlombard, kuniyu, michael.christie,
linux-scsi, target-devel, linux-kernel, bilbao
On Fri, Apr 03, 2026 at 06:44:29PM -0700, carlos.bilbao@kernel.org wrote:
> From: Carlos Bilbao <carlos.bilbao@kernel.org>
>
> If ecdb_ahdr->ahslength is zero, two bugs follow:
>
> kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15, ...)
>
> allocates 15 bytes, but the immediately following memcpy writes
> ISCSI_CDB_SIZE (16) bytes into it, a one-byte heap overflow. Also:
>
> memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
> be16_to_cpu(ecdb_ahdr->ahslength) - 1);
>
> (u16)0 - 1 promotes to (int)-1 which converts to SIZE_MAX as size_t,
> causing a massive out-of-bounds write.
>
> Reject ahslength == 0 with ISCSI_REASON_PROTOCOL_ERROR before the kmalloc.
>
> Fixes: 8f1f7d297bce ("scsi: target: iscsi: Add support for extended CDB AHS")
> Signed-off-by: Carlos Bilbao (Lambda) <carlos.bilbao@kernel.org>
> ---
> drivers/target/iscsi/iscsi_target.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
> index e80449f6ce15..8db24d35c762 100644
> --- a/drivers/target/iscsi/iscsi_target.c
> +++ b/drivers/target/iscsi/iscsi_target.c
> @@ -1100,6 +1100,8 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
> cdb = hdr->cdb;
>
> if (hdr->hlength) {
> + u16 ahslength;
> +
> ecdb_ahdr = (struct iscsi_ecdb_ahdr *) (hdr + 1);
> if (ecdb_ahdr->ahstype != ISCSI_AHSTYPE_CDB) {
> pr_err("Additional Header Segment type %d not supported!\n",
> @@ -1108,14 +1110,19 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
> ISCSI_REASON_CMD_NOT_SUPPORTED, buf);
> }
>
> - cdb = kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15,
> - GFP_KERNEL);
> + ahslength = be16_to_cpu(ecdb_ahdr->ahslength);
> + if (!ahslength) {
> + pr_err("Extended CDB AHS with zero length, protocol error.\n");
> + return iscsit_add_reject_cmd(cmd,
> + ISCSI_REASON_PROTOCOL_ERROR, buf);
> + }
> +
For a complete solution please add a check that AHS fits in the buffer.
ahslength must be less or equal than ((hdr->hlength * 4) - 3).
> + cdb = kmalloc(ahslength + 15, GFP_KERNEL);
It took some time to recall what did 15 mean. May be make it clear for
everyone too?
u16 cdb_length = ahslength - 1 + ISCSI_CDB_SIZE;
cdb = kmalloc(cdb_length, GFP_KERNEL);
memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, cdb_length - ISCSI_CDB_SIZE);
> if (cdb == NULL)
> return iscsit_add_reject_cmd(cmd,
> ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
> memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
> - memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
> - be16_to_cpu(ecdb_ahdr->ahslength) - 1);
> + memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, ahslength - 1);
> }
>
> data_direction = (hdr->flags & ISCSI_FLAG_CMD_WRITE) ? DMA_TO_DEVICE :
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] scsi: target: iscsi: reject zero-length Extended CDB AHS
2026-04-07 9:23 ` Dmitry Bogdanov
@ 2026-04-09 2:23 ` Carlos Bilbao
0 siblings, 0 replies; 5+ messages in thread
From: Carlos Bilbao @ 2026-04-09 2:23 UTC (permalink / raw)
To: Dmitry Bogdanov, carlos.bilbao
Cc: martin.petersen, kees, pabeni, mlombard, kuniyu, michael.christie,
linux-scsi, target-devel, linux-kernel, bilbao
Hello,
On 4/7/26 02:23, Dmitry Bogdanov wrote:
> On Fri, Apr 03, 2026 at 06:44:29PM -0700, carlos.bilbao@kernel.org wrote:
>> From: Carlos Bilbao <carlos.bilbao@kernel.org>
>>
>> If ecdb_ahdr->ahslength is zero, two bugs follow:
>>
>> kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15, ...)
>>
>> allocates 15 bytes, but the immediately following memcpy writes
>> ISCSI_CDB_SIZE (16) bytes into it, a one-byte heap overflow. Also:
>>
>> memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
>> be16_to_cpu(ecdb_ahdr->ahslength) - 1);
>>
>> (u16)0 - 1 promotes to (int)-1 which converts to SIZE_MAX as size_t,
>> causing a massive out-of-bounds write.
>>
>> Reject ahslength == 0 with ISCSI_REASON_PROTOCOL_ERROR before the kmalloc.
>>
>> Fixes: 8f1f7d297bce ("scsi: target: iscsi: Add support for extended CDB AHS")
>> Signed-off-by: Carlos Bilbao (Lambda) <carlos.bilbao@kernel.org>
>> ---
>> drivers/target/iscsi/iscsi_target.c | 15 +++++++++++----
>> 1 file changed, 11 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
>> index e80449f6ce15..8db24d35c762 100644
>> --- a/drivers/target/iscsi/iscsi_target.c
>> +++ b/drivers/target/iscsi/iscsi_target.c
>> @@ -1100,6 +1100,8 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
>> cdb = hdr->cdb;
>>
>> if (hdr->hlength) {
>> + u16 ahslength;
>> +
>> ecdb_ahdr = (struct iscsi_ecdb_ahdr *) (hdr + 1);
>> if (ecdb_ahdr->ahstype != ISCSI_AHSTYPE_CDB) {
>> pr_err("Additional Header Segment type %d not supported!\n",
>> @@ -1108,14 +1110,19 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
>> ISCSI_REASON_CMD_NOT_SUPPORTED, buf);
>> }
>>
>> - cdb = kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15,
>> - GFP_KERNEL);
>> + ahslength = be16_to_cpu(ecdb_ahdr->ahslength);
>> + if (!ahslength) {
>> + pr_err("Extended CDB AHS with zero length, protocol error.\n");
>> + return iscsit_add_reject_cmd(cmd,
>> + ISCSI_REASON_PROTOCOL_ERROR, buf);
>> + }
>> +
> For a complete solution please add a check that AHS fits in the buffer.
> ahslength must be less or equal than ((hdr->hlength * 4) - 3).
For sure, I'll send a v2 including that.
>
>> + cdb = kmalloc(ahslength + 15, GFP_KERNEL);
> It took some time to recall what did 15 mean. May be make it clear for
> everyone too?
>
> u16 cdb_length = ahslength - 1 + ISCSI_CDB_SIZE;
> cdb = kmalloc(cdb_length, GFP_KERNEL);
> memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
> memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, cdb_length - ISCSI_CDB_SIZE);
>
Agreed!
>> if (cdb == NULL)
>> return iscsit_add_reject_cmd(cmd,
>> ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
>> memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
>> - memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
>> - be16_to_cpu(ecdb_ahdr->ahslength) - 1);
>> + memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, ahslength - 1);
>> }
>>
>> data_direction = (hdr->flags & ISCSI_FLAG_CMD_WRITE) ? DMA_TO_DEVICE :
>> --
>> 2.43.0
>>
Thanks,
Carlos
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] scsi: target: iscsi: reject invalid size Extended CDB AHS
2026-04-04 1:44 [PATCH] scsi: target: iscsi: reject zero-length Extended CDB AHS carlos.bilbao
2026-04-07 9:23 ` Dmitry Bogdanov
@ 2026-04-09 2:42 ` carlos.bilbao
2026-04-09 9:31 ` Dmitry Bogdanov
1 sibling, 1 reply; 5+ messages in thread
From: carlos.bilbao @ 2026-04-09 2:42 UTC (permalink / raw)
To: d.bogdanov
Cc: bilbao, martin.petersen, kees, linux-kernel, linux-scsi,
Carlos Bilbao
From: Carlos Bilbao <carlos.bilbao@kernel.org>
If ecdb_ahdr->ahslength is zero, two bugs follow:
kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15, ...)
allocates 15 bytes, but the immediately following memcpy writes
ISCSI_CDB_SIZE (16) bytes into it, a one-byte heap overflow. Also:
memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
be16_to_cpu(ecdb_ahdr->ahslength) - 1);
(u16)0 - 1 promotes to (int)-1 which converts to SIZE_MAX as size_t,
causing a massive out-of-bounds write.
Reject ahslength == 0 with ISCSI_REASON_PROTOCOL_ERROR before the kmalloc.
Also reject ahslength values that exceed the actual AHS buffer advertised.
Changes in v2:
- Add bounds check: ahslength must not exceed (hdr->hlength * 4) - 3.
- Replace opaque ahslength + 15 with explicit cdb_length variable.
Fixes: 8f1f7d297bce ("scsi: target: iscsi: Add support for extended CDB AHS")
Signed-off-by: Carlos Bilbao (Lambda) <carlos.bilbao@kernel.org>
---
drivers/target/iscsi/iscsi_target.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index e80449f6ce15..1a492965ebdf 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1100,6 +1100,8 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
cdb = hdr->cdb;
if (hdr->hlength) {
+ u16 ahslength;
+
ecdb_ahdr = (struct iscsi_ecdb_ahdr *) (hdr + 1);
if (ecdb_ahdr->ahstype != ISCSI_AHSTYPE_CDB) {
pr_err("Additional Header Segment type %d not supported!\n",
@@ -1108,14 +1110,27 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
ISCSI_REASON_CMD_NOT_SUPPORTED, buf);
}
- cdb = kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15,
- GFP_KERNEL);
+ ahslength = be16_to_cpu(ecdb_ahdr->ahslength);
+ if (!ahslength) {
+ pr_err("Extended CDB AHS with zero length, protocol error.\n");
+ return iscsit_add_reject_cmd(cmd,
+ ISCSI_REASON_PROTOCOL_ERROR, buf);
+ }
+ if (ahslength > (hdr->hlength * 4) - 3) {
+ pr_err("Extended CDB AHS length %u exceeds available buffer.\n",
+ ahslength);
+ return iscsit_add_reject_cmd(cmd,
+ ISCSI_REASON_PROTOCOL_ERROR, buf);
+ }
+
+ u16 cdb_length = ahslength - 1 + ISCSI_CDB_SIZE;
+
+ cdb = kmalloc(cdb_length, GFP_KERNEL);
if (cdb == NULL)
return iscsit_add_reject_cmd(cmd,
ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
- memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
- be16_to_cpu(ecdb_ahdr->ahslength) - 1);
+ memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, cdb_length - ISCSI_CDB_SIZE);
}
data_direction = (hdr->flags & ISCSI_FLAG_CMD_WRITE) ? DMA_TO_DEVICE :
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] scsi: target: iscsi: reject invalid size Extended CDB AHS
2026-04-09 2:42 ` [PATCH v2] scsi: target: iscsi: reject invalid size " carlos.bilbao
@ 2026-04-09 9:31 ` Dmitry Bogdanov
0 siblings, 0 replies; 5+ messages in thread
From: Dmitry Bogdanov @ 2026-04-09 9:31 UTC (permalink / raw)
To: carlos.bilbao; +Cc: bilbao, martin.petersen, kees, linux-kernel, linux-scsi
On Wed, Apr 08, 2026 at 07:42:53PM -0700, carlos.bilbao@kernel.org wrote:
>
> From: Carlos Bilbao <carlos.bilbao@kernel.org>
>
> If ecdb_ahdr->ahslength is zero, two bugs follow:
>
> kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15, ...)
>
> allocates 15 bytes, but the immediately following memcpy writes
> ISCSI_CDB_SIZE (16) bytes into it, a one-byte heap overflow. Also:
>
> memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
> be16_to_cpu(ecdb_ahdr->ahslength) - 1);
>
> (u16)0 - 1 promotes to (int)-1 which converts to SIZE_MAX as size_t,
> causing a massive out-of-bounds write.
>
> Reject ahslength == 0 with ISCSI_REASON_PROTOCOL_ERROR before the kmalloc.
> Also reject ahslength values that exceed the actual AHS buffer advertised.
>
> Changes in v2:
>
> - Add bounds check: ahslength must not exceed (hdr->hlength * 4) - 3.
> - Replace opaque ahslength + 15 with explicit cdb_length variable.
>
> Fixes: 8f1f7d297bce ("scsi: target: iscsi: Add support for extended CDB AHS")
> Signed-off-by: Carlos Bilbao (Lambda) <carlos.bilbao@kernel.org>
Reviewed-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
> ---
> drivers/target/iscsi/iscsi_target.c | 23 +++++++++++++++++++----
> 1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
> index e80449f6ce15..1a492965ebdf 100644
> --- a/drivers/target/iscsi/iscsi_target.c
> +++ b/drivers/target/iscsi/iscsi_target.c
> @@ -1100,6 +1100,8 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
> cdb = hdr->cdb;
>
> if (hdr->hlength) {
> + u16 ahslength;
> +
> ecdb_ahdr = (struct iscsi_ecdb_ahdr *) (hdr + 1);
> if (ecdb_ahdr->ahstype != ISCSI_AHSTYPE_CDB) {
> pr_err("Additional Header Segment type %d not supported!\n",
> @@ -1108,14 +1110,27 @@ int iscsit_setup_scsi_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd,
> ISCSI_REASON_CMD_NOT_SUPPORTED, buf);
> }
>
> - cdb = kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15,
> - GFP_KERNEL);
> + ahslength = be16_to_cpu(ecdb_ahdr->ahslength);
> + if (!ahslength) {
> + pr_err("Extended CDB AHS with zero length, protocol error.\n");
> + return iscsit_add_reject_cmd(cmd,
> + ISCSI_REASON_PROTOCOL_ERROR, buf);
> + }
> + if (ahslength > (hdr->hlength * 4) - 3) {
> + pr_err("Extended CDB AHS length %u exceeds available buffer.\n",
> + ahslength);
> + return iscsit_add_reject_cmd(cmd,
> + ISCSI_REASON_PROTOCOL_ERROR, buf);
> + }
> +
> + u16 cdb_length = ahslength - 1 + ISCSI_CDB_SIZE;
AFAIK, a variable declarationis allowed to be in the beginning of code block only.
> +
> + cdb = kmalloc(cdb_length, GFP_KERNEL);
> if (cdb == NULL)
> return iscsit_add_reject_cmd(cmd,
> ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
> memcpy(cdb, hdr->cdb, ISCSI_CDB_SIZE);
> - memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb,
> - be16_to_cpu(ecdb_ahdr->ahslength) - 1);
> + memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, cdb_length - ISCSI_CDB_SIZE);
> }
>
> data_direction = (hdr->flags & ISCSI_FLAG_CMD_WRITE) ? DMA_TO_DEVICE :
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2026-04-09 9:32 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-04-04 1:44 [PATCH] scsi: target: iscsi: reject zero-length Extended CDB AHS carlos.bilbao
2026-04-07 9:23 ` Dmitry Bogdanov
2026-04-09 2:23 ` Carlos Bilbao
2026-04-09 2:42 ` [PATCH v2] scsi: target: iscsi: reject invalid size " carlos.bilbao
2026-04-09 9:31 ` Dmitry Bogdanov
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