Unverified Commit 0f166bf1 authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Christian Brauner
Browse files

select: store end_time as timespec64 in restart block 



Storing the end time seconds as 'unsigned long' can lead to truncation
on 32-bit architectures if assigned from the 64-bit timespec64::tv_sec.
As the select() core uses timespec64 consistently, also use that in the
restart block.

This also allows the simplification of the accessors.

Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20251223-restart-block-expiration-v2-1-8e33e5df7359@linutronix.de


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 3685744a

fs/select.c

+4 −8
Original line number Diff line number Diff line
@@ -1038,14 +1038,11 @@ static long do_restart_poll(struct restart_block *restart_block) 
{

	struct pollfd __user *ufds = restart_block->poll.ufds;

	int nfds = restart_block->poll.nfds;

	struct timespec64 *to = NULL, end_time;

	struct timespec64 *to = NULL;

	int ret;



	if (restart_block->poll.has_timeout) {

		end_time.tv_sec = restart_block->poll.tv_sec;

		end_time.tv_nsec = restart_block->poll.tv_nsec;

		to = &end_time;

	}

	if (restart_block->poll.has_timeout)

		to = &restart_block->poll.end_time;



	ret = do_sys_poll(ufds, nfds, to);
@@ -1077,8 +1074,7 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds, 
		restart_block->poll.nfds = nfds;



		if (timeout_msecs >= 0) {

			restart_block->poll.tv_sec = end_time.tv_sec;

			restart_block->poll.tv_nsec = end_time.tv_nsec;

			restart_block->poll.end_time = end_time;

			restart_block->poll.has_timeout = 1;

		} else

			restart_block->poll.has_timeout = 0;

include/linux/restart_block.h

+2 −2
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#define __LINUX_RESTART_BLOCK_H



#include <linux/compiler.h>

#include <linux/time64.h>

#include <linux/types.h>



struct __kernel_timespec;
@@ -50,8 +51,7 @@ struct restart_block { 
			struct pollfd __user *ufds;

			int nfds;

			int has_timeout;

			unsigned long tv_sec;

			unsigned long tv_nsec;

			struct timespec64 end_time;

		} poll;

	};

};