Commit 4d36a9e6 authored Oct 25, 2008 by Arjan van de Ven Committed by Linus Torvalds Oct 26, 2008

select: deal with math overflow from borderline valid userland data



Some userland apps seem to pass in a "0" for the seconds, and several
seconds worth of usecs to select().  The old kernels accepted this just
fine, so the new kernels must too.

However, due to the upscaling of the microseconds to nanoseconds we had
some cases where we got math overflow, and depending on the GCC version
(due to inlining decisions) that actually resulted in an -EINVAL return.

This patch fixes this by adding the excess microseconds to the seconds
field.

Also with thanks to Marcin Slusarz for spotting some implementation bugs
in the diagnostics patches.

Reported-by: Carlos R. Mafra <crmafra2@gmail.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 44a504c4

fs/compat.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1684,8 +1684,9 @@ asmlinkage long compat_sys_select(int n, compat_ulong_t __user *inp,
		return -EFAULT;

		to = &end_time;
		if (poll_select_set_timeout(to, tv.tv_sec,
		tv.tv_usec * NSEC_PER_USEC))
		if (poll_select_set_timeout(to,
		tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
		(tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
		return -EINVAL;
		}

fs/select.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -519,8 +519,9 @@ asmlinkage long sys_select(int n, fd_set __user inp, fd_set __user outp,
		return -EFAULT;

		to = &end_time;
		if (poll_select_set_timeout(to, tv.tv_sec,
		tv.tv_usec * NSEC_PER_USEC))
		if (poll_select_set_timeout(to,
		tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
		(tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
		return -EINVAL;
		}

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