| From: Danilo Krummrich <danilokrummrich@dk-develop.de> |
| Date: Tue, 10 Apr 2018 16:31:38 -0700 |
| Subject: fs/proc/proc_sysctl.c: fix potential page fault while unregistering |
| sysctl table |
| |
| commit a0b0d1c345d0317efe594df268feb5ccc99f651e upstream. |
| |
| proc_sys_link_fill_cache() does not take currently unregistering sysctl |
| tables into account, which might result into a page fault in |
| sysctl_follow_link() - add a check to fix it. |
| |
| This bug has been present since v3.4. |
| |
| Link: http://lkml.kernel.org/r/20180228013506.4915-1-danilokrummrich@dk-develop.de |
| Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets") |
| Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de> |
| Acked-by: Kees Cook <keescook@chromium.org> |
| Reviewed-by: Andrew Morton <akpm@linux-foundation.org> |
| Cc: "Luis R . Rodriguez" <mcgrof@kernel.org> |
| Cc: "Eric W. Biederman" <ebiederm@xmission.com> |
| Cc: Alexey Dobriyan <adobriyan@gmail.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/proc/proc_sysctl.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/fs/proc/proc_sysctl.c |
| +++ b/fs/proc/proc_sysctl.c |
| @@ -654,7 +654,10 @@ static bool proc_sys_link_fill_cache(str |
| struct ctl_table *table) |
| { |
| bool ret = true; |
| + |
| head = sysctl_head_grab(head); |
| + if (IS_ERR(head)) |
| + return false; |
| |
| if (S_ISLNK(table->mode)) { |
| /* It is not an error if we can not follow the link ignore it */ |
