From: Tetsuo Handa <[email protected]>
Subject: kernel/kmod.c: check for NULL in call_usermodehelper_exec()
If /proc/sys/kernel/core_pattern contains only "|", NULL pointer
dereference happens upon core dump because argv_split("") returns argv[0]
== NULL.
This bug was once fixed by commit 264b83c0 ("usermodehelper: check
subprocess_info->path != NULL") but was by error reintroduced by commit
7f57cfa4 ("usermodehelper: kill the sub_info->path[0] check").
This bug seems to exist since 2.6.19 (the version which core dump to pipe
was added). Depending on kernel version and config, some side effect
might happen immediately after this oops (e.g. kernel panic with
2.6.32-358.18.1.el6).
Signed-off-by: Tetsuo Handa <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
kernel/kmod.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN kernel/kmod.c~kernel-kmodc-check-for-null-in-call_usermodehelper_exec
kernel/kmod.c
--- a/kernel/kmod.c~kernel-kmodc-check-for-null-in-call_usermodehelper_exec
+++ a/kernel/kmod.c
@@ -571,6 +571,10 @@ int call_usermodehelper_exec(struct subp
DECLARE_COMPLETION_ONSTACK(done);
int retval = 0;
+ if (!sub_info->path) {
+ call_usermodehelper_freeinfo(sub_info);
+ return -EINVAL;
+ }
helper_lock();
if (!khelper_wq || usermodehelper_disabled) {
retval = -EBUSY;
_
--
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