From: Dan Carpenter <dan.carpenter@oracle.com> stable inclusion from stable-v4.19.102 commit 732ecd4aad51d336b49b9be431219d173ac826c8 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6L0EC CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: tong tiangen <tongtiangen@huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- mm/mempolicy.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 4cac46d56f38..4769ed2ed7f3 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2886,6 +2886,9 @@ 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'; @@ -2896,9 +2899,6 @@ 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; -- 2.25.1