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iov_iter_get_pages{,_alloc}(): cap the maxsize with MAX_RW_COUNT

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All callers can and should handle iov_iter_get_pages() returning
fewer pages than requested.  All in-kernel ones do.  And it makes
the arithmetical overflow analysis much simpler...

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-06-11 16:44:21 -04:00
parent 18fa9af726
commit 7392ed1734
1 changed files with 4 additions and 0 deletions
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4
lib/iov_iter.c
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@ -1348,6 +1348,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
maxsize = i->count; maxsize = i->count;
if (!maxsize) if (!maxsize)
return 0; return 0;
if (maxsize > MAX_RW_COUNT)
maxsize = MAX_RW_COUNT;
if (likely(iter_is_iovec(i))) { if (likely(iter_is_iovec(i))) {
unsigned int gup_flags = 0; unsigned int gup_flags = 0;
@ -1474,6 +1476,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
maxsize = i->count; maxsize = i->count;
if (!maxsize) if (!maxsize)
return 0; return 0;
if (maxsize > MAX_RW_COUNT)
maxsize = MAX_RW_COUNT;
if (likely(iter_is_iovec(i))) { if (likely(iter_is_iovec(i))) {
unsigned int gup_flags = 0; unsigned int gup_flags = 0;