4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 8aa37bde1a7b645816cda8b80df4753ecf172bf1 upstream.
both callers have verified that fd is not greater than ->max_fds;
however, misprediction might end up with
tofree = fdt->fd[fd];
being speculatively executed. That's wrong for the same reasons
why it's wrong in close_fd()/file_close_fd_locked(); the same
solution applies - array_index_nospec(fd, fdt->max_fds) could differ
from fd only in case of speculative execution on mispredicted path.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/file.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/file.c
+++ b/fs/file.c
@@ -879,6 +879,7 @@ __releases(&files->file_lock)
* tables and this condition does not arise without those.
*/
fdt = files_fdtable(files);
+ fd = array_index_nospec(fd, fdt->max_fds);
tofree = fdt->fd[fd];
if (!tofree && fd_is_open(fd, fdt))
goto Ebusy;
