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| author | Dan Carpenter <dan.carpenter@oracle.com> | 2020-01-30 22:11:07 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-01-31 10:30:36 -0800 |
| commit | c7a91bc7c2e17e0a9c8b9745a2cb118891218fd1 (patch) | |
| tree | fccd4e057c6e40e98fae5cf9d381539ab6ea17c1 /mm/mempolicy.c | |
| parent | 68f23b89067fdf187763e75a56087550624fdbee (diff) | |
| download | lwn-c7a91bc7c2e17e0a9c8b9745a2cb118891218fd1.tar.gz lwn-c7a91bc7c2e17e0a9c8b9745a2cb118891218fd1.zip | |
mm/mempolicy.c: fix out of bounds write in mpol_parse_str()
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>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index b2920ae87a61..977c641f78cf 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2821,6 +2821,9 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) char *flags = strchr(str, '='); int err = 1, mode; + if (flags) + *flags++ = '\0'; /* terminate mode string */ + if (nodelist) { /* NUL-terminate mode or flags string */ *nodelist++ = '\0'; @@ -2831,9 +2834,6 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) } else nodes_clear(nodes); - if (flags) - *flags++ = '\0'; /* terminate mode string */ - mode = match_string(policy_modes, MPOL_MAX, str); if (mode < 0) goto out; |