[PATCH AUTOSEL 5.6 089/606] fix multiplication overflow in copy_fdtable()

Sasha Levin
2020-06-08T23:17:12Z

From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 4e89b7210403fa4a8acafe7c602b6212b7af6c3b ]

cpy and set really should be size_t; we won't get an overflow on that,
since sysctl_nr_open can't be set above ~(size_t)0 / sizeof(void *),
so nr that would've managed to overflow size_t on that multiplication
won't get anywhere near copy_fdtable() - we'll fail with EMFILE
before that.

Cc: stable@kernel.org # v2.6.25+
Fixes: 9cfe015aa424 (get rid of NR_OPEN and introduce a sysctl_nr_open)
Reported-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/file.c b/fs/file.c
index c8a4e4c86e55..abb8b7081d7a 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -70,7 +70,7 @@ static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt,
*/
static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
{
- unsigned int cpy, set;
+ size_t cpy, set;

BUG_ON(nfdt->max_fds < ofdt->max_fds);

--
2.25.1