[PATCH v9 01/17] iov_iter: Fix iov_iter_get_pages{,_alloc} page fault return value
From: Andreas Gruenbacher <agruenba@redhat.com>
Date: 2021-11-02 12:30:06
Also in:
linux-fsdevel, lkml, ocfs2-devel
Subsystem:
library code, the rest, userspace copyin/copyout (uiovec) · Maintainers:
Andrew Morton, Linus Torvalds, Alexander Viro
Both iov_iter_get_pages and iov_iter_get_pages_alloc return the number of bytes of the iovec they could get the pages for. When they cannot get any pages, they're supposed to return 0, but when the start of the iovec isn't page aligned, the calculation goes wrong and they return a negative value. Fix both functions. In addition, change iov_iter_get_pages_alloc to return NULL in that case to prevent resource leaks. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> --- lib/iov_iter.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 755c10c5138c..60b5e6edfbaa 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c@@ -1488,7 +1488,7 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, res = get_user_pages_fast(addr, n, iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, pages); - if (unlikely(res < 0)) + if (unlikely(res <= 0)) return res; return (res == n ? len : res * PAGE_SIZE) - *start; }
@@ -1612,8 +1612,9 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, return -ENOMEM; res = get_user_pages_fast(addr, n, iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p); - if (unlikely(res < 0)) { + if (unlikely(res <= 0)) { kvfree(p); + *pages = NULL; return res; } *pages = p;
--
2.31.1