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Message-Id: <20180528100245.407668837@linuxfoundation.org>
Date: Mon, 28 May 2018 12:01:27 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Danilo Krummrich <danilokrummrich@...develop.de>,
Kees Cook <keescook@...omium.org>,
Andrew Morton <akpm@...ux-foundation.org>,
"Luis R . Rodriguez" <mcgrof@...nel.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Alexey Dobriyan <adobriyan@...il.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.16 054/272] fs/proc/proc_sysctl.c: fix potential page fault while unregistering sysctl table
4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Danilo Krummrich <danilokrummrich@...develop.de>
[ Upstream commit a0b0d1c345d0317efe594df268feb5ccc99f651e ]
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@...develop.de>
Acked-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Luis R . Rodriguez" <mcgrof@...nel.org>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
fs/proc/proc_sysctl.c | 3 +++
1 file changed, 3 insertions(+)
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -707,7 +707,10 @@ 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 */
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