for fcntl64 with F_GETLK64 we need use checking against COMPAT_LOFF_T_MAX. Fixes: 94073ad77fff2 "fs/locks: don't mess with the address limit in compat_fcntl64"
Signed-off-by: Vitaly Lipatov <[email protected]> --- fs/fcntl.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index 30f47d0..fa17f67 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -604,6 +604,25 @@ static int fixup_compat_flock(struct flock *flock) return 0; } +/* + * GETLK64 was successful and we need to return the data, but it needs to fit in + * the compat structure. + * l_start shouldn't be too big, unless the original start + end is greater than + * COMPAT_LOFF_T_MAX, in which case the app was asking for trouble, so we return + * -EOVERFLOW in that case. l_len could be too big, in which case we just + * truncate it, and only allow the app to see that part of the conflicting lock + * that might make sense to it anyway + */ + +static int fixup_compat_l_flock(struct flock *flock) +{ + if (flock->l_start > COMPAT_LOFF_T_MAX) + return -EOVERFLOW; + if (flock->l_len > COMPAT_LOFF_T_MAX) + flock->l_len = COMPAT_LOFF_T_MAX; + return 0; +} + COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, compat_ulong_t, arg) { @@ -644,7 +663,7 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); if (err) break; - err = fixup_compat_flock(&flock); + err = fixup_compat_l_flock(&flock); if (err) return err; err = put_compat_flock64(&flock, compat_ptr(arg)); -- 2.10.4
