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| author | Jiri Slaby <jslaby@suse.cz> | 2017-06-13 13:35:51 +0200 |
|---|---|---|
| committer | Jeff Layton <jlayton@redhat.com> | 2017-06-14 08:46:45 -0400 |
| commit | fc3dc67471461c0efcb1ed22fb7595121d65fad9 (patch) | |
| tree | 6f1fa906e1e74da646bcf0511ad71a849e4a8302 /fs/fcntl.c | |
| parent | 393cc3f51135ea2520521f776ef3afdf3395c797 (diff) | |
| download | linux-fc3dc67471461c0efcb1ed22fb7595121d65fad9.tar.bz2 | |
fs/fcntl: f_setown, avoid undefined behaviour
fcntl(0, F_SETOWN, 0x80000000) triggers:
UBSAN: Undefined behaviour in fs/fcntl.c:118:7
negation of -2147483648 cannot be represented in type 'int':
CPU: 1 PID: 18261 Comm: syz-executor Not tainted 4.8.1-0-syzkaller #1
...
Call Trace:
...
[<ffffffffad8f0868>] ? f_setown+0x1d8/0x200
[<ffffffffad8f19a9>] ? SyS_fcntl+0x999/0xf30
[<ffffffffaed1fb00>] ? entry_SYSCALL_64_fastpath+0x23/0xc1
Fix that by checking the arg parameter properly (against INT_MAX) before
"who = -who". And return immediatelly with -EINVAL in case it is wrong.
Note that according to POSIX we can return EINVAL:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html
[EINVAL]
The cmd argument is F_SETOWN and the value of the argument
is not valid as a process or process group identifier.
[v2] returns an error, v1 used to fail silently
[v3] implement proper check for the bad value INT_MIN
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jeff Layton <jlayton@poochiereds.net>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'fs/fcntl.c')
| -rw-r--r-- | fs/fcntl.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c index 313eba860346..693322e28751 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -116,6 +116,10 @@ int f_setown(struct file *filp, unsigned long arg, int force) int who = arg; type = PIDTYPE_PID; if (who < 0) { + /* avoid overflow below */ + if (who == INT_MIN) + return -EINVAL; + type = PIDTYPE_PGID; who = -who; } |