* [PATCH] audit: fix a memleak caused by auditing load module
@ 2019-03-05 11:14 Li RongQing
2019-03-05 14:18 ` Paul Moore
0 siblings, 1 reply; 3+ messages in thread
From: Li RongQing @ 2019-03-05 11:14 UTC (permalink / raw)
To: paul, eparis, linux-audit, linux-kernel
we should always free context->module.name, since it will be
allocated unconditionally and audit_log_start() can fail with
other reasons, and audit_log_exit maybe not called
unreferenced object 0xffff88af90837d20 (size 8):
comm "modprobe", pid 1036, jiffies 4294704867 (age 3069.138s)
hex dump (first 8 bytes):
69 78 67 62 65 00 ff ff ixgbe...
backtrace:
[<0000000008da28fe>] __audit_log_kern_module+0x33/0x80
[<00000000c1491e61>] load_module+0x64f/0x3850
[<000000007fc9ae3f>] __do_sys_init_module+0x218/0x250
[<0000000000d4a478>] do_syscall_64+0x117/0x400
[<000000004924ded8>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[<000000007dc331dd>] 0xffffffffffffffff
Fixes: ca86cad7380e3 ("audit: log module name on init_module")
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
kernel/auditsc.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b2d1f043f..2bd80375f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1186,8 +1186,13 @@ static void show_special(struct audit_context *context, int *call_panic)
int i;
ab = audit_log_start(context, GFP_KERNEL, context->type);
- if (!ab)
+ if (!ab) {
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
return;
+ }
switch (context->type) {
case AUDIT_SOCKETCALL: {
@@ -1354,8 +1359,15 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
context->personality = tsk->personality;
ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL);
- if (!ab)
+
+ if (!ab) {
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
return; /* audit_panic has been called */
+ }
+
audit_log_format(ab, "arch=%x syscall=%d",
context->arch, context->major);
if (context->personality != PER_LINUX)
@@ -1576,6 +1588,12 @@ void __audit_syscall_exit(int success, long return_code)
if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
audit_log_exit(context, current);
+ else {
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
+ }
context->in_syscall = 0;
context->prio = context->state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;
--
2.16.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] audit: fix a memleak caused by auditing load module
2019-03-05 11:14 [PATCH] audit: fix a memleak caused by auditing load module Li RongQing
@ 2019-03-05 14:18 ` Paul Moore
2019-03-06 3:23 ` 答复: " Li,Rongqing
0 siblings, 1 reply; 3+ messages in thread
From: Paul Moore @ 2019-03-05 14:18 UTC (permalink / raw)
To: Li RongQing; +Cc: Eric Paris, linux-audit, linux-kernel
On Tue, Mar 5, 2019 at 6:14 AM Li RongQing <lirongqing@baidu.com> wrote:
> we should always free context->module.name, since it will be
> allocated unconditionally and audit_log_start() can fail with
> other reasons, and audit_log_exit maybe not called
>
> unreferenced object 0xffff88af90837d20 (size 8):
> comm "modprobe", pid 1036, jiffies 4294704867 (age 3069.138s)
> hex dump (first 8 bytes):
> 69 78 67 62 65 00 ff ff ixgbe...
> backtrace:
> [<0000000008da28fe>] __audit_log_kern_module+0x33/0x80
> [<00000000c1491e61>] load_module+0x64f/0x3850
> [<000000007fc9ae3f>] __do_sys_init_module+0x218/0x250
> [<0000000000d4a478>] do_syscall_64+0x117/0x400
> [<000000004924ded8>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> [<000000007dc331dd>] 0xffffffffffffffff
>
> Fixes: ca86cad7380e3 ("audit: log module name on init_module")
> Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
> kernel/auditsc.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index b2d1f043f..2bd80375f 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1186,8 +1186,13 @@ static void show_special(struct audit_context *context, int *call_panic)
> int i;
>
> ab = audit_log_start(context, GFP_KERNEL, context->type);
> - if (!ab)
> + if (!ab) {
> + if (context->type == AUDIT_KERN_MODULE) {
> + kfree(context->module.name);
> + context->module.name = NULL;
> + }
> return;
> + }
Hello.
Thanks for the patch, but I have to ask if you've considered freeing
the module name in audit_free_context()? That seems like the correct
way to solve this issue.
-Paul
--
paul moore
www.paul-moore.com
^ permalink raw reply [flat|nested] 3+ messages in thread
* 答复: [PATCH] audit: fix a memleak caused by auditing load module
2019-03-05 14:18 ` Paul Moore
@ 2019-03-06 3:23 ` Li,Rongqing
0 siblings, 0 replies; 3+ messages in thread
From: Li,Rongqing @ 2019-03-06 3:23 UTC (permalink / raw)
To: Paul Moore; +Cc: Eric Paris, linux-audit, linux-kernel
> -----邮件原件-----
> 发件人: Paul Moore [mailto:paul@paul-moore.com]
> 发送时间: 2019年3月5日 22:18
> 收件人: Li,Rongqing <lirongqing@baidu.com>
> 抄送: Eric Paris <eparis@redhat.com>; linux-audit@redhat.com;
> linux-kernel@vger.kernel.org
> 主题: Re: [PATCH] audit: fix a memleak caused by auditing load module
>
> On Tue, Mar 5, 2019 at 6:14 AM Li RongQing <lirongqing@baidu.com> wrote:
> > we should always free context->module.name, since it will be allocated
> > unconditionally and audit_log_start() can fail with other reasons, and
> > audit_log_exit maybe not called
> >
> > unreferenced object 0xffff88af90837d20 (size 8):
> > comm "modprobe", pid 1036, jiffies 4294704867 (age 3069.138s)
> > hex dump (first 8 bytes):
> > 69 78 67 62 65 00 ff ff ixgbe...
> > backtrace:
> > [<0000000008da28fe>] __audit_log_kern_module+0x33/0x80
> > [<00000000c1491e61>] load_module+0x64f/0x3850
> > [<000000007fc9ae3f>] __do_sys_init_module+0x218/0x250
> > [<0000000000d4a478>] do_syscall_64+0x117/0x400
> > [<000000004924ded8>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > [<000000007dc331dd>] 0xffffffffffffffff
> >
> > Fixes: ca86cad7380e3 ("audit: log module name on init_module")
> > Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> > ---
> > kernel/auditsc.c | 22 ++++++++++++++++++++--
> > 1 file changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c index
> > b2d1f043f..2bd80375f 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -1186,8 +1186,13 @@ static void show_special(struct audit_context
> *context, int *call_panic)
> > int i;
> >
> > ab = audit_log_start(context, GFP_KERNEL, context->type);
> > - if (!ab)
> > + if (!ab) {
> > + if (context->type == AUDIT_KERN_MODULE) {
> > + kfree(context->module.name);
> > + context->module.name = NULL;
> > + }
> > return;
> > + }
>
> Hello.
>
> Thanks for the patch, but I have to ask if you've considered freeing the module
> name in audit_free_context()? That seems like the correct way to solve this
> issue.
>
It does not work that move the freeing of module.name in audit_free_context
Since we should free module.name based on context->types is AUDIT_KERN_MODULE,
but __audit_syscall_exit is called first, and will set context->type to 0,
When audit_free_context is called, context->type is 0, will cause to fail.
I will change this patches as below:
commit ee32ec2354b47a824e5e63d4f46567d577a02824 (HEAD -> master)
Author: Li RongQing <lirongqing@baidu.com>
Date: Tue Mar 5 15:42:09 2019 +0800
audit: fix a memleak caused by auditing load module
module.name will be allocated unconditionally when auditing load
module, and audit_log_start() can fail with other reasons, or
audit_log_exit maybe not called, caused module.name is released
so always free module.name in audit_free_context
unreferenced object 0xffff88af90837d20 (size 8):
comm "modprobe", pid 1036, jiffies 4294704867 (age 3069.138s)
hex dump (first 8 bytes):
69 78 67 62 65 00 ff ff ixgbe...
backtrace:
[<0000000008da28fe>] __audit_log_kern_module+0x33/0x80
[<00000000c1491e61>] load_module+0x64f/0x3850
[<000000007fc9ae3f>] __do_sys_init_module+0x218/0x250
[<0000000000d4a478>] do_syscall_64+0x117/0x400
[<000000004924ded8>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[<000000007dc331dd>] 0xffffffffffffffff
Fixes: ca86cad7380e3 ("audit: log module name on init_module")
Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b2d1f043f..07728b07a 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -964,6 +964,9 @@ int audit_alloc(struct task_struct *tsk)
static inline void audit_free_context(struct audit_context *context)
{
+ if (context->type == AUDIT_KERN_MODULE)
+ kfree(context->module.name);
+
audit_free_names(context);
unroll_tree_refs(context, NULL, 0);
free_tree_refs(context);
@@ -1282,6 +1285,8 @@ static void show_special(struct audit_context *context, int *call_panic)
if (context->module.name) {
audit_log_untrustedstring(ab, context->module.name);
kfree(context->module.name);
+ context->module.name = NULL;
+ context->type = 0;
} else
audit_log_format(ab, "(null)");
@@ -1583,6 +1588,11 @@ void __audit_syscall_exit(int success, long return_code)
if (!list_empty(&context->killed_trees))
audit_kill_trees(&context->killed_trees);
+ if (context->type == AUDIT_KERN_MODULE) {
+ kfree(context->module.name);
+ context->module.name = NULL;
+ }
+
audit_free_names(context);
unroll_tree_refs(context, NULL, 0);
audit_free_aux(context);
-RongQing
> -Paul
>
> --
> paul moore
> www.paul-moore.com
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2019-03-05 11:14 [PATCH] audit: fix a memleak caused by auditing load module Li RongQing
2019-03-05 14:18 ` Paul Moore
2019-03-06 3:23 ` 答复: " Li,Rongqing
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