* FAILED: patch "[PATCH] scsi: target: iscsi: Bound iscsi_encode_text_output() appends" failed to apply to 5.15-stable tree
@ 2026-06-04 10:50 gregkh
2026-06-05 20:34 ` [PATCH 5.15.y] scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf Sasha Levin
0 siblings, 1 reply; 2+ messages in thread
From: gregkh @ 2026-06-04 10:50 UTC (permalink / raw)
To: michael.bommarito, john.g.garry, martin.petersen; +Cc: stable
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x bf33e01f88388c43e285492a63e539df6ffed64c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026060410-slam-conch-e2f1@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From bf33e01f88388c43e285492a63e539df6ffed64c Mon Sep 17 00:00:00 2001
From: Michael Bommarito <michael.bommarito@gmail.com>
Date: Mon, 11 May 2026 14:49:14 -0400
Subject: [PATCH] scsi: target: iscsi: Bound iscsi_encode_text_output() appends
to rsp_buf
iscsi_encode_text_output() concatenates "key=value\0" records into
login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer
allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call
sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check
the remaining buffer capacity:
*length += sprintf(output_buf, "%s=%s", er->key, er->value);
*length += 1;
output_buf = textbuf + *length;
The 8192-byte ceiling at iscsi_target_check_login_request() bounds the
*input* Login PDU payload, but a single PDU can carry up to 2048 minimal
four-byte "a=b\0" pairs, each unknown key expanding to a 16-byte
"a=NotUnderstood\0" output record via iscsi_add_notunderstood_response().
2048 * 16 = 32 KiB of output into an 8 KiB buffer, producing a ~24 KiB
heap overrun in the kmalloc-8k slab.
The fix introduces a static iscsi_encode_text_record() helper that uses
snprintf() with a per-call bounds check against the remaining buffer,
and threads a u32 textbuf_size parameter through
iscsi_encode_text_output(). Both call sites in
iscsi_target_handle_csg_zero() (PHASE_SECURITY) and
iscsi_target_handle_csg_one() (PHASE_OPERATIONAL) pass
MAX_KEY_VALUE_PAIRS. On overflow the encoder logs the condition, calls
iscsi_release_extra_responses() to drop queued records, and returns -1;
both caller sites now emit ISCSI_STATUS_CLS_INITIATOR_ERR /
ISCSI_LOGIN_STATUS_INIT_ERR via iscsit_tx_login_rsp() before returning,
so the initiator sees an explicit failed-login response rather than a
silent connection drop. (Prior to this patch only the PHASE_OPERATIONAL
caller did that; the PHASE_SECURITY caller is converted to the same
shape.)
Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Tested-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 832588f21f91..b03ed154ca34 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -899,10 +899,14 @@ static int iscsi_target_handle_csg_zero(
SENDER_TARGET,
login->rsp_buf,
&login->rsp_length,
+ MAX_KEY_VALUE_PAIRS,
conn->param_list,
conn->tpg->tpg_attrib.login_keys_workaround);
- if (ret < 0)
+ if (ret < 0) {
+ iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
+ ISCSI_LOGIN_STATUS_INIT_ERR);
return -1;
+ }
if (!iscsi_check_negotiated_keys(conn->param_list)) {
bool auth_required = iscsi_conn_auth_required(conn);
@@ -986,6 +990,7 @@ static int iscsi_target_handle_csg_one(struct iscsit_conn *conn, struct iscsi_lo
SENDER_TARGET,
login->rsp_buf,
&login->rsp_length,
+ MAX_KEY_VALUE_PAIRS,
conn->param_list,
conn->tpg->tpg_attrib.login_keys_workaround);
if (ret < 0) {
diff --git a/drivers/target/iscsi/iscsi_target_parameters.c b/drivers/target/iscsi/iscsi_target_parameters.c
index 4ed578c7b98d..2b318b13268e 100644
--- a/drivers/target/iscsi/iscsi_target_parameters.c
+++ b/drivers/target/iscsi/iscsi_target_parameters.c
@@ -1371,19 +1371,42 @@ int iscsi_decode_text_input(
return -1;
}
+/*
+ * Append "key=value" plus a trailing NUL into @textbuf at *@length.
+ * Returns 0 on success and advances *@length, or -EMSGSIZE if the
+ * record (including the NUL) would not fit in the remaining buffer.
+ */
+static int iscsi_encode_text_record(char *textbuf, u32 *length,
+ u32 textbuf_size,
+ const char *key, const char *value)
+{
+ int n;
+ u32 avail;
+
+ if (*length >= textbuf_size)
+ return -EMSGSIZE;
+
+ avail = textbuf_size - *length;
+ n = snprintf(textbuf + *length, avail, "%s=%s", key, value);
+ if (n < 0 || (u32)n + 1 > avail)
+ return -EMSGSIZE;
+
+ *length += n + 1;
+ return 0;
+}
+
int iscsi_encode_text_output(
u8 phase,
u8 sender,
char *textbuf,
u32 *length,
+ u32 textbuf_size,
struct iscsi_param_list *param_list,
bool keys_workaround)
{
- char *output_buf = NULL;
struct iscsi_extra_response *er;
struct iscsi_param *param;
-
- output_buf = textbuf + *length;
+ int ret;
if (iscsi_enforce_integrity_rules(phase, param_list) < 0)
return -1;
@@ -1395,10 +1418,12 @@ int iscsi_encode_text_output(
!IS_PSTATE_RESPONSE_SENT(param) &&
!IS_PSTATE_REPLY_OPTIONAL(param) &&
(param->phase & phase)) {
- *length += sprintf(output_buf, "%s=%s",
- param->name, param->value);
- *length += 1;
- output_buf = textbuf + *length;
+ ret = iscsi_encode_text_record(textbuf, length,
+ textbuf_size,
+ param->name,
+ param->value);
+ if (ret < 0)
+ goto err_overflow;
SET_PSTATE_RESPONSE_SENT(param);
pr_debug("Sending key: %s=%s\n",
param->name, param->value);
@@ -1408,10 +1433,12 @@ int iscsi_encode_text_output(
!IS_PSTATE_ACCEPTOR(param) &&
!IS_PSTATE_PROPOSER(param) &&
(param->phase & phase)) {
- *length += sprintf(output_buf, "%s=%s",
- param->name, param->value);
- *length += 1;
- output_buf = textbuf + *length;
+ ret = iscsi_encode_text_record(textbuf, length,
+ textbuf_size,
+ param->name,
+ param->value);
+ if (ret < 0)
+ goto err_overflow;
SET_PSTATE_PROPOSER(param);
iscsi_check_proposer_for_optional_reply(param,
keys_workaround);
@@ -1421,14 +1448,21 @@ int iscsi_encode_text_output(
}
list_for_each_entry(er, ¶m_list->extra_response_list, er_list) {
- *length += sprintf(output_buf, "%s=%s", er->key, er->value);
- *length += 1;
- output_buf = textbuf + *length;
+ ret = iscsi_encode_text_record(textbuf, length, textbuf_size,
+ er->key, er->value);
+ if (ret < 0)
+ goto err_overflow;
pr_debug("Sending key: %s=%s\n", er->key, er->value);
}
iscsi_release_extra_responses(param_list);
return 0;
+
+err_overflow:
+ pr_err("iSCSI login response buffer (%u bytes) exhausted, dropping login.\n",
+ textbuf_size);
+ iscsi_release_extra_responses(param_list);
+ return -1;
}
int iscsi_check_negotiated_keys(struct iscsi_param_list *param_list)
diff --git a/drivers/target/iscsi/iscsi_target_parameters.h b/drivers/target/iscsi/iscsi_target_parameters.h
index c672a971fcb7..38d2238dfe08 100644
--- a/drivers/target/iscsi/iscsi_target_parameters.h
+++ b/drivers/target/iscsi/iscsi_target_parameters.h
@@ -43,7 +43,7 @@ extern struct iscsi_param *iscsi_find_param_from_key(char *, struct iscsi_param_
extern int iscsi_extract_key_value(char *, char **, char **);
extern int iscsi_update_param_value(struct iscsi_param *, char *);
extern int iscsi_decode_text_input(u8, u8, char *, u32, struct iscsit_conn *);
-extern int iscsi_encode_text_output(u8, u8, char *, u32 *,
+extern int iscsi_encode_text_output(u8, u8, char *, u32 *, u32,
struct iscsi_param_list *, bool);
extern int iscsi_check_negotiated_keys(struct iscsi_param_list *);
extern void iscsi_set_connection_parameters(struct iscsi_conn_ops *,
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 5.15.y] scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
2026-06-04 10:50 FAILED: patch "[PATCH] scsi: target: iscsi: Bound iscsi_encode_text_output() appends" failed to apply to 5.15-stable tree gregkh
@ 2026-06-05 20:34 ` Sasha Levin
0 siblings, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2026-06-05 20:34 UTC (permalink / raw)
To: stable; +Cc: Michael Bommarito, John Garry, Martin K. Petersen, Sasha Levin
From: Michael Bommarito <michael.bommarito@gmail.com>
[ Upstream commit bf33e01f88388c43e285492a63e539df6ffed64c ]
iscsi_encode_text_output() concatenates "key=value\0" records into
login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer
allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call
sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check
the remaining buffer capacity:
*length += sprintf(output_buf, "%s=%s", er->key, er->value);
*length += 1;
output_buf = textbuf + *length;
The 8192-byte ceiling at iscsi_target_check_login_request() bounds the
*input* Login PDU payload, but a single PDU can carry up to 2048 minimal
four-byte "a=b\0" pairs, each unknown key expanding to a 16-byte
"a=NotUnderstood\0" output record via iscsi_add_notunderstood_response().
2048 * 16 = 32 KiB of output into an 8 KiB buffer, producing a ~24 KiB
heap overrun in the kmalloc-8k slab.
The fix introduces a static iscsi_encode_text_record() helper that uses
snprintf() with a per-call bounds check against the remaining buffer,
and threads a u32 textbuf_size parameter through
iscsi_encode_text_output(). Both call sites in
iscsi_target_handle_csg_zero() (PHASE_SECURITY) and
iscsi_target_handle_csg_one() (PHASE_OPERATIONAL) pass
MAX_KEY_VALUE_PAIRS. On overflow the encoder logs the condition, calls
iscsi_release_extra_responses() to drop queued records, and returns -1;
both caller sites now emit ISCSI_STATUS_CLS_INITIATOR_ERR /
ISCSI_LOGIN_STATUS_INIT_ERR via iscsit_tx_login_rsp() before returning,
so the initiator sees an explicit failed-login response rather than a
silent connection drop. (Prior to this patch only the PHASE_OPERATIONAL
caller did that; the PHASE_SECURITY caller is converted to the same
shape.)
Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Tested-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/target/iscsi/iscsi_target_nego.c | 7 ++-
.../target/iscsi/iscsi_target_parameters.c | 62 ++++++++++++++-----
.../target/iscsi/iscsi_target_parameters.h | 2 +-
3 files changed, 55 insertions(+), 16 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 32a2852352db1c..2ff2cbdd2598f9 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -870,10 +870,14 @@ static int iscsi_target_handle_csg_zero(
SENDER_TARGET,
login->rsp_buf,
&login->rsp_length,
+ MAX_KEY_VALUE_PAIRS,
conn->param_list,
conn->tpg->tpg_attrib.login_keys_workaround);
- if (ret < 0)
+ if (ret < 0) {
+ iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
+ ISCSI_LOGIN_STATUS_INIT_ERR);
return -1;
+ }
if (!iscsi_check_negotiated_keys(conn->param_list)) {
if (conn->tpg->tpg_attrib.authentication &&
@@ -941,6 +945,7 @@ static int iscsi_target_handle_csg_one(struct iscsi_conn *conn, struct iscsi_log
SENDER_TARGET,
login->rsp_buf,
&login->rsp_length,
+ MAX_KEY_VALUE_PAIRS,
conn->param_list,
conn->tpg->tpg_attrib.login_keys_workaround);
if (ret < 0) {
diff --git a/drivers/target/iscsi/iscsi_target_parameters.c b/drivers/target/iscsi/iscsi_target_parameters.c
index 62004e3fe1ccc3..74624c67d189d1 100644
--- a/drivers/target/iscsi/iscsi_target_parameters.c
+++ b/drivers/target/iscsi/iscsi_target_parameters.c
@@ -1419,19 +1419,42 @@ int iscsi_decode_text_input(
return -1;
}
+/*
+ * Append "key=value" plus a trailing NUL into @textbuf at *@length.
+ * Returns 0 on success and advances *@length, or -EMSGSIZE if the
+ * record (including the NUL) would not fit in the remaining buffer.
+ */
+static int iscsi_encode_text_record(char *textbuf, u32 *length,
+ u32 textbuf_size,
+ const char *key, const char *value)
+{
+ int n;
+ u32 avail;
+
+ if (*length >= textbuf_size)
+ return -EMSGSIZE;
+
+ avail = textbuf_size - *length;
+ n = snprintf(textbuf + *length, avail, "%s=%s", key, value);
+ if (n < 0 || (u32)n + 1 > avail)
+ return -EMSGSIZE;
+
+ *length += n + 1;
+ return 0;
+}
+
int iscsi_encode_text_output(
u8 phase,
u8 sender,
char *textbuf,
u32 *length,
+ u32 textbuf_size,
struct iscsi_param_list *param_list,
bool keys_workaround)
{
- char *output_buf = NULL;
struct iscsi_extra_response *er;
struct iscsi_param *param;
-
- output_buf = textbuf + *length;
+ int ret;
if (iscsi_enforce_integrity_rules(phase, param_list) < 0)
return -1;
@@ -1443,10 +1466,12 @@ int iscsi_encode_text_output(
!IS_PSTATE_RESPONSE_SENT(param) &&
!IS_PSTATE_REPLY_OPTIONAL(param) &&
(param->phase & phase)) {
- *length += sprintf(output_buf, "%s=%s",
- param->name, param->value);
- *length += 1;
- output_buf = textbuf + *length;
+ ret = iscsi_encode_text_record(textbuf, length,
+ textbuf_size,
+ param->name,
+ param->value);
+ if (ret < 0)
+ goto err_overflow;
SET_PSTATE_RESPONSE_SENT(param);
pr_debug("Sending key: %s=%s\n",
param->name, param->value);
@@ -1456,10 +1481,12 @@ int iscsi_encode_text_output(
!IS_PSTATE_ACCEPTOR(param) &&
!IS_PSTATE_PROPOSER(param) &&
(param->phase & phase)) {
- *length += sprintf(output_buf, "%s=%s",
- param->name, param->value);
- *length += 1;
- output_buf = textbuf + *length;
+ ret = iscsi_encode_text_record(textbuf, length,
+ textbuf_size,
+ param->name,
+ param->value);
+ if (ret < 0)
+ goto err_overflow;
SET_PSTATE_PROPOSER(param);
iscsi_check_proposer_for_optional_reply(param,
keys_workaround);
@@ -1469,14 +1496,21 @@ int iscsi_encode_text_output(
}
list_for_each_entry(er, ¶m_list->extra_response_list, er_list) {
- *length += sprintf(output_buf, "%s=%s", er->key, er->value);
- *length += 1;
- output_buf = textbuf + *length;
+ ret = iscsi_encode_text_record(textbuf, length, textbuf_size,
+ er->key, er->value);
+ if (ret < 0)
+ goto err_overflow;
pr_debug("Sending key: %s=%s\n", er->key, er->value);
}
iscsi_release_extra_responses(param_list);
return 0;
+
+err_overflow:
+ pr_err("iSCSI login response buffer (%u bytes) exhausted, dropping login.\n",
+ textbuf_size);
+ iscsi_release_extra_responses(param_list);
+ return -1;
}
int iscsi_check_negotiated_keys(struct iscsi_param_list *param_list)
diff --git a/drivers/target/iscsi/iscsi_target_parameters.h b/drivers/target/iscsi/iscsi_target_parameters.h
index 240c4c4344f691..6d02d19eb8cf0f 100644
--- a/drivers/target/iscsi/iscsi_target_parameters.h
+++ b/drivers/target/iscsi/iscsi_target_parameters.h
@@ -46,7 +46,7 @@ extern struct iscsi_param *iscsi_find_param_from_key(char *, struct iscsi_param_
extern int iscsi_extract_key_value(char *, char **, char **);
extern int iscsi_update_param_value(struct iscsi_param *, char *);
extern int iscsi_decode_text_input(u8, u8, char *, u32, struct iscsi_conn *);
-extern int iscsi_encode_text_output(u8, u8, char *, u32 *,
+extern int iscsi_encode_text_output(u8, u8, char *, u32 *, u32,
struct iscsi_param_list *, bool);
extern int iscsi_check_negotiated_keys(struct iscsi_param_list *);
extern void iscsi_set_connection_parameters(struct iscsi_conn_ops *,
--
2.53.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
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2026-06-04 10:50 FAILED: patch "[PATCH] scsi: target: iscsi: Bound iscsi_encode_text_output() appends" failed to apply to 5.15-stable tree gregkh
2026-06-05 20:34 ` [PATCH 5.15.y] scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf Sasha Levin
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