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Linus Torvalds authored
The iov_iter_advance() function would look at the iov->iov_len entry even though it might have iterated over the whole array, and iov was pointing past the end. This would cause DEBUG_PAGEALLOC to trigger a kernel page fault if the allocation was at the end of a page, and the next page was unallocated. The quick fix is to just change the order of the tests: check that there is any iovec data left before we check the iov entry itself. Thanks to Alexey Dobriyan for finding this case, and testing the fix. Reported-and-tested-by:
Alexey Dobriyan <adobriyan@gmail.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x] Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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