do_coredump() accesses helper_argv[0] without checking helper_argv != NULL.
Though, likely helper_argv != NULL.
Below versions have this problem.
2.6.24.7
2.6.25.20
2.6.26.8
2.6.27.10
2.6.28-rc9
mmotm 2008-12-22-16-14
Signed-off-by: Tetsuo Handa <[email protected]>
---
fs/exec.c | 5 +++++
1 file changed, 5 insertions(+)
--- linux-2.6.28-rc9-mm1.orig/fs/exec.c
+++ linux-2.6.28-rc9-mm1/fs/exec.c
@@ -1809,10 +1809,15 @@ int do_coredump(long signr, int exit_cod
if ((!ispipe) && (core_limit < binfmt->min_coredump))
goto fail_unlock;
if (ispipe) {
helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
+ if (!helper_argv) {
+ printk(KERN_WARNING "%s failed to allocate memory\n",
+ __func__);
+ goto fail_unlock;
+ }
/* Terminate the string before the first option */
delimit = strchr(corename, ' ');
if (delimit)
*delimit = '\0';
delimit = strrchr(helper_argv[0], '/');
On Wed, Dec 24, 2008 at 03:16:16PM +0900, Tetsuo Handa wrote:
>do_coredump() accesses helper_argv[0] without checking helper_argv != NULL.
>Though, likely helper_argv != NULL.
>
>Below versions have this problem.
>
> 2.6.24.7
> 2.6.25.20
> 2.6.26.8
> 2.6.27.10
> 2.6.28-rc9
> mmotm 2008-12-22-16-14
>
>Signed-off-by: Tetsuo Handa <[email protected]>
>---
> fs/exec.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
>--- linux-2.6.28-rc9-mm1.orig/fs/exec.c
>+++ linux-2.6.28-rc9-mm1/fs/exec.c
>@@ -1809,10 +1809,15 @@ int do_coredump(long signr, int exit_cod
> if ((!ispipe) && (core_limit < binfmt->min_coredump))
> goto fail_unlock;
>
> if (ispipe) {
> helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
>+ if (!helper_argv) {
>+ printk(KERN_WARNING "%s failed to allocate memory\n",
>+ __func__);
>+ goto fail_unlock;
How about going to the line:
current->fsuid = fsuid;
? Because when argv_split() fails, helper_argv is NULL and doesn't need
to be checked again.
Otherwise,
Reviewed-by: WANG Cong <[email protected]>
Thanks.
--
"Against stupidity, the gods themselves, contend in vain."
Hello.
Am$(D+1(Brico Wang wrote:
> How about going to the line:
>
> current->fsuid = fsuid;
>
> ? Because when argv_split() fails, helper_argv is NULL and doesn't need
> to be checked again.
I didn't understand what you say. I'm saying that
"do_coredump() may accesss helper_argv[0] when helper_argv == NULL",
which will result in "NULL pointer dereference" problem.
Yes, this problem unlikely happens. Thus,
if (!helper_argv)
goto fail_unlock;
may be enough.
Regards.
On Fri, Dec 26, 2008 at 04:00:56PM +0900, Tetsuo Handa wrote:
>Hello.
>
>Am$(D+1rico Wang wrote:
>> How about going to the line:
>>
>> current->fsuid = fsuid;
>>
>> ? Because when argv_split() fails, helper_argv is NULL and doesn't need
>> to be checked again.
>
>I didn't understand what you say. I'm saying that
>"do_coredump() may accesss helper_argv[0] when helper_argv == NULL",
>which will result in "NULL pointer dereference" problem.
>Yes, this problem unlikely happens. Thus,
>
>if (!helper_argv)
> goto fail_unlock;
>
>may be enough.
>
Yes, goto fail_unlock will go to this line:
if (helper_argv)
argv_free(helper_argv);
but in this situation, helper_argv is known as NULL, thus another
check doesn't need. So we can go to the line below, i.e.
fail_unlock:
if (helper_argv)
argv_free(helper_argv);
current->fsuid = fsuid; //<=== goto this line
coredump_finish(mm);
You need to add a new label, of course. :)
--
"Against stupidity, the gods themselves, contend in vain."
Hello.
Americo Wang wrote:
> fail_unlock:
> if (helper_argv)
> argv_free(helper_argv);
>
> current->fsuid = fsuid; //<=== goto this line
> coredump_finish(mm);
>
> You need to add a new label, of course. :)
>
Ah, you were talking about destination of goto statement. I see.
Unfortunately, -mm source uses "revert_creds(old_cred); put_cred(cred);"
instead of "current->fsuid = fsuid;".
To keep this patch applicable to all afftected versions,
I'd like not to introduce a new label.
> if (helper_argv)
> argv_free(helper_argv);
Well, I think it's better to check "if (helper_argv)" inside argv_free()
in case the caller forgets to check.
Regards.
--------------------
Subject: Check return from argv_split() in do_coredump().
do_coredump() accesses helper_argv[0] without checking helper_argv != NULL.
Though, likely helper_argv != NULL.
Below versions have this problem.
2.6.24.7
2.6.25.20
2.6.26.8
2.6.27.10
2.6.28
mmotm 2008-12-24-01-20
Signed-off-by: Tetsuo Handa <[email protected]>
---
fs/exec.c | 2 ++
1 file changed, 2 insertions(+)
--- linux-2.6.28-rc9-mm1.orig/fs/exec.c
+++ linux-2.6.28-rc9-mm1/fs/exec.c
@@ -1808,6 +1808,8 @@ int do_coredump(long signr, int exit_cod
if (ispipe) {
helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
+ if (!helper_argv)
+ goto fail_unlock;
/* Terminate the string before the first option */
delimit = strchr(corename, ' ');
if (delimit)
> --------------------
> Subject: Check return from argv_split() in do_coredump().
>
> do_coredump() accesses helper_argv[0] without checking helper_argv != NULL.
> Though, likely helper_argv != NULL.
>
> Below versions have this problem.
>
> 2.6.24.7
> 2.6.25.20
> 2.6.26.8
> 2.6.27.10
> 2.6.28
> mmotm 2008-12-24-01-20
please remove target version from patch description (it is not useful
for git log).
and please cc to linux-stable.
otherthings, looks good to me.
Reviewed-by: KOSAKI Motohiro <[email protected]>