| From: Dan Carpenter <dan.carpenter@oracle.com> |
| Date: Thu, 30 Jan 2020 22:11:07 -0800 |
| Subject: 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> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| mm/mempolicy.c | 6 +++--- |
| 1 file changed, 3 insertions(+), 3 deletions(-) |
| |
| --- a/mm/mempolicy.c |
| +++ b/mm/mempolicy.c |
| @@ -2687,6 +2687,9 @@ int mpol_parse_str(char *str, struct mem |
| char *flags = strchr(str, '='); |
| int err = 1; |
| |
| + if (flags) |
| + *flags++ = '\0'; /* terminate mode string */ |
| + |
| if (nodelist) { |
| /* NUL-terminate mode or flags string */ |
| *nodelist++ = '\0'; |
| @@ -2697,9 +2700,6 @@ int mpol_parse_str(char *str, struct mem |
| } 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; |
