Fix off-by-one error in iov_iter_advance()

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 <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: <[email protected]> [2.6.25.x, 2.6.26.x]
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions