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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>
This commit is contained in:
Arjan van de Ven 2008-10-25 12:41:41 -07:00 committed by Linus Torvalds
parent 44a504c405
commit 4d36a9e65d
2 changed files with 6 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
fs/compat.c
View File

@ -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;
}

5
fs/select.c
View File

@ -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;
}