3.16.60-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Danilo Krummrich <danilokrummr...@dk-develop.de> 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-danilokrummr...@dk-develop.de Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets") Signed-off-by: Danilo Krummrich <danilokrummr...@dk-develop.de> Acked-by: Kees Cook <keesc...@chromium.org> Reviewed-by: Andrew Morton <a...@linux-foundation.org> Cc: "Luis R . Rodriguez" <mcg...@kernel.org> Cc: "Eric W. Biederman" <ebied...@xmission.com> Cc: Alexey Dobriyan <adobri...@gmail.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Ben Hutchings <b...@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 */
