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v0.8.1
https://github.com/torvalds/linux
02 December 2023, 22:23:51 UTC
Revision b6a8b316c667f914c198a2de62e6729f359b7931 authored by Thomas Gleixner on 02 April 2007, 12:25:31 UTC, committed by Linus Torvalds on 02 April 2007, 17:07:25 UTC 
[PATCH] i386: fix file_read_actor() and pipe_read() for original i386 systems
 
The __copy_to_user_inatomic() calls in file_read_actor() and pipe_read()
are broken on original i386 machines, where WP-works-ok == false, as
__copy_to_user_inatomic() on such systems calls functions which might
sleep and/or contain cond_resched() calls inside of a kmap_atomic()
region.

The original check for WP-works-ok was in access_ok(), but got moved
during the 2.5 series to fix a race vs. swap.

Return the number of bytes to copy in the case where we are in an atomic
region, so the non atomic code pathes in file_read_actor() and
pipe_read() are taken.

This could be optimized to avoid the kmap_atomicby moving the check for
WP-works-ok into fault_in_pages_writeable(), but this is more intrusive
and can be done later.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent f991519
History
Tip revision: b6a8b316c667f914c198a2de62e6729f359b7931 authored by Thomas Gleixner on 02 April 2007, 12:25:31 UTC
[PATCH] i386: fix file_read_actor() and pipe_read() for original i386 systems
Tip revision: b6a8b31
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