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author | Dan Carpenter <dan.carpenter@oracle.com> | 2020-01-30 22:11:07 -0800 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2020-05-22 21:19:40 +0100 |
commit | ee0ea94e91498b2c1f57749280d57752326f5928 (patch) | |
tree | 3582e4884c2b73b34638ebc5c2fe5341fa33f4c8 | |
parent | dd18bacf6d75ae5d84641d30409b3b397d0412ca (diff) | |
download | linux-stable-ee0ea94e91498b2c1f57749280d57752326f5928.tar.gz linux-stable-ee0ea94e91498b2c1f57749280d57752326f5928.tar.bz2 linux-stable-ee0ea94e91498b2c1f57749280d57752326f5928.zip |
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>
-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 ad5f8f16270c..11fee39672ee 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2687,6 +2687,9 @@ 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'; @@ -2697,9 +2700,6 @@ 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; |