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 <lav@xxxxxxxxxxx>
---
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
