From: Al Viro Date: Tue, 27 Apr 2021 16:34:04 +0000 (-0400) Subject: copy_page_to_iter(): fix ITER_DISCARD case X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=a506abc7b644d71966a75337d5a534f531b3cdc4;p=linux.git copy_page_to_iter(): fix ITER_DISCARD case we need to advance the iterator... Cc: stable@vger.kernel.org Signed-off-by: Al Viro --- diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 12fb04b231437..c8877cffb7bc0 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -965,9 +965,12 @@ static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes size_t wanted = copy_to_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; - } else if (unlikely(iov_iter_is_discard(i))) + } else if (unlikely(iov_iter_is_discard(i))) { + if (unlikely(i->count < bytes)) + bytes = i->count; + i->count -= bytes; return bytes; - else if (likely(!iov_iter_is_pipe(i))) + } else if (likely(!iov_iter_is_pipe(i))) return copy_page_to_iter_iovec(page, offset, bytes, i); else return copy_page_to_iter_pipe(page, offset, bytes, i);