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authorDan Carpenter <dan.carpenter@oracle.com>2020-01-31 09:11:07 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-02-05 17:18:13 +0300
commit569ae81e2ed8eab6c3b99d7364ef129f8c21f193 (patch)
treebe3818242b766095759efc7252823c61f743740d /mm
parent08e4a312439c294b9753166537baf3cc0bd6bb07 (diff)
downloadlinux-569ae81e2ed8eab6c3b99d7364ef129f8c21f193.tar.xz
mm/mempolicy.c: fix out of bounds write in mpol_parse_str()
commit c7a91bc7c2e17e0a9c8b9745a2cb118891218fd1 upstream. What we are trying to do is change the '=' character to a NUL terminator and then at the end of the function we restore it back to an '='. The problem is there are two error paths where we jump to the end of the function before we have replaced the '=' with NUL. We end up putting the '=' in the wrong place (possibly one element before the start of the buffer). Link: http://lkml.kernel.org/r/20200115055426.vdjwvry44nfug7yy@kili.mountain Reported-by: syzbot+e64a13c5369a194d67df@syzkaller.appspotmail.com Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Dmitry Vyukov <dvyukov@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mempolicy.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index a37cfa88669e..1b34f2e35951 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2724,6 +2724,9 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
char *flags = strchr(str, '=');
int err = 1;
+ if (flags)
+ *flags++ = '\0'; /* terminate mode string */
+
if (nodelist) {
/* NUL-terminate mode or flags string */
*nodelist++ = '\0';
@@ -2734,9 +2737,6 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
} else
nodes_clear(nodes);
- if (flags)
- *flags++ = '\0'; /* terminate mode string */
-
for (mode = 0; mode < MPOL_MAX; mode++) {
if (!strcmp(str, policy_modes[mode])) {
break;