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authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-05-25 14:47:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-05-25 18:12:11 -0700
commit23d6aef74da86a33fa6bb75f79565e0a16ee97c2 (patch)
tree553228677345d3d48ebd0d795ef69dfa00871ede
parenta21558618c5dfc55b6086743a88ce5a9c1588f0a (diff)
downloadlinux-stericsson-23d6aef74da86a33fa6bb75f79565e0a16ee97c2.tar.gz
kernel/sys.c: fix potential Spectre v1 issue
`resource' can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: kernel/sys.c:1474 __do_compat_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap) kernel/sys.c:1455 __do_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap) Fix this by sanitizing *resource* before using it to index current->signal->rlim Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Link: http://lkml.kernel.org/r/20180515030038.GA11822@embeddedor.com Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/sys.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index b0eee418ee0d..d1b2b8d934bb 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -71,6 +71,9 @@
#include <asm/io.h>
#include <asm/unistd.h>
+/* Hardening for Spectre-v1 */
+#include <linux/nospec.h>
+
#include "uid16.h"
#ifndef SET_UNALIGN_CTL
@@ -1453,6 +1456,7 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
if (resource >= RLIM_NLIMITS)
return -EINVAL;
+ resource = array_index_nospec(resource, RLIM_NLIMITS);
task_lock(current->group_leader);
x = current->signal->rlim[resource];
task_unlock(current->group_leader);
@@ -1472,6 +1476,7 @@ COMPAT_SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
if (resource >= RLIM_NLIMITS)
return -EINVAL;
+ resource = array_index_nospec(resource, RLIM_NLIMITS);
task_lock(current->group_leader);
r = current->signal->rlim[resource];
task_unlock(current->group_leader);