Commit 7b847446 authored Nov 21, 2019 by Dmitry Safonov Committed by Thomas Gleixner Nov 21, 2019

time: Zero the upper 32-bits in __kernel_timespec on 32-bit



On compat interfaces, the high order bits of nanoseconds should be zeroed
out. This is because the application code or the libc do not guarantee
zeroing of these. If used without zeroing, kernel might be at risk of using
timespec values incorrectly.

Originally it was handled correctly, but lost during is_compat_syscall()
cleanup. Revert the condition back to check CONFIG_64BIT.

Fixes: 98f76206 ("compat: Cleanup in_compat_syscall() callers")
Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191121000303.126523-1-dima@arista.com

parent af42d346

kernel/time/time.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -881,7 +881,8 @@ int get_timespec64(struct timespec64 *ts,
		ts->tv_sec = kts.tv_sec;

		/* Zero out the padding for 32 bit systems or in compat mode */
		if (IS_ENABLED(CONFIG_64BIT_TIME) && in_compat_syscall())
		if (IS_ENABLED(CONFIG_64BIT_TIME) && (!IS_ENABLED(CONFIG_64BIT) \|\|
		in_compat_syscall()))
		kts.tv_nsec &= 0xFFFFFFFFUL;

		ts->tv_nsec = kts.tv_nsec;

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