Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5611e119 authored by Yuntao Wang's avatar Yuntao Wang Committed by Greg Kroah-Hartman
Browse files

fs/file: fix the check in find_next_fd() 



[ Upstream commit ed8c7fbdfe117abbef81f65428ba263118ef298a ]

The maximum possible return value of find_next_zero_bit(fdt->full_fds_bits,
maxbit, bitbit) is maxbit. This return value, multiplied by BITS_PER_LONG,
gives the value of bitbit, which can never be greater than maxfd, it can
only be equal to maxfd at most, so the following check 'if (bitbit > maxfd)'
will never be true.

Moreover, when bitbit equals maxfd, it indicates that there are no unused
fds, and the function can directly return.

Fix this check.

Signed-off-by: default avatarYuntao Wang <yuntao.wang@linux.dev>
Link: https://lore.kernel.org/r/20240529160656.209352-1-yuntao.wang@linux.dev


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent b366d898

fs/file.c

+2 −2
Original line number Diff line number Diff line
@@ -462,12 +462,12 @@ struct files_struct init_files = { 


static unsigned int find_next_fd(struct fdtable *fdt, unsigned int start)

{

	unsigned int maxfd = fdt->max_fds;

	unsigned int maxfd = fdt->max_fds; /* always multiple of BITS_PER_LONG */

	unsigned int maxbit = maxfd / BITS_PER_LONG;

	unsigned int bitbit = start / BITS_PER_LONG;



	bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG;

	if (bitbit > maxfd)

	if (bitbit >= maxfd)

		return maxfd;

	if (bitbit > start)

		start = bitbit;