__close_fd() is reachable via the close() syscall with a userspace-controlled fd. Ensure that it can't be used to speculatively access past the end of current->fdt. Reported-by: Omer Tripp <trippo@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Hackmann <ghackmann@xxxxxxxxxx> --- fs/file.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/file.c b/fs/file.c index 7ffd6e9d103d..a80cf82be96b 100644 --- a/fs/file.c +++ b/fs/file.c @@ -18,6 +18,7 @@ #include <linux/bitops.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <linux/nospec.h> unsigned int sysctl_nr_open __read_mostly = 1024*1024; unsigned int sysctl_nr_open_min = BITS_PER_LONG; @@ -626,6 +627,7 @@ int __close_fd(struct files_struct *files, unsigned fd) fdt = files_fdtable(files); if (fd >= fdt->max_fds) goto out_unlock; + fd = array_index_nospec(fd, fdt->max_fds); file = fdt->fd[fd]; if (!file) goto out_unlock; -- 2.19.0.397.gdd90340f6a-goog
