[PATCH 6.8 653/715] io_uring: Fix release of pinned pages when __io_uaddr_map fails

Sasha Levin
2024-03-24T22:45:46Z

From: Gabriel Krisman Bertazi <krisman@suse.de>

[ Upstream commit 67d1189d1095d471ed7fa426c7e384a7140a5dd7 ]

Looking at the error path of __io_uaddr_map, if we fail after pinning
the pages for any reasons, ret will be set to -EINVAL and the error
handler won't properly release the pinned pages.

I didn't manage to trigger it without forcing a failure, but it can
happen in real life when memory is heavily fragmented.

Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Fixes: 223ef4743164 ("io_uring: don't allow IORING_SETUP_NO_MMAP rings on highmem pages")
Link: https://lore.kernel.org/r/20240313213912.1920-1-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
io_uring/io_uring.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 030cc930d1c6a..9f938874c5e13 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2702,7 +2702,7 @@ static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
struct page **page_array;
unsigned int nr_pages;
void *page_addr;
- int ret, i;
+ int ret, i, pinned;

*npages = 0;

@@ -2716,12 +2716,12 @@ static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
if (!page_array)
return ERR_PTR(-ENOMEM);

- ret = pin_user_pages_fast(uaddr, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
- page_array);
- if (ret != nr_pages) {
-err:
- io_pages_free(&page_array, ret > 0 ? ret : 0);
- return ret < 0 ? ERR_PTR(ret) : ERR_PTR(-EFAULT);
+
+ pinned = pin_user_pages_fast(uaddr, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
+ page_array);
+ if (pinned != nr_pages) {
+ ret = (pinned < 0) ? pinned : -EFAULT;
+ goto free_pages;
}

page_addr = page_address(page_array[0]);
@@ -2735,7 +2735,7 @@ static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
* didn't support this feature.
*/
if (PageHighMem(page_array[i]))
- goto err;
+ goto free_pages;

/*
* No support for discontig pages for now, should either be a
@@ -2744,13 +2744,17 @@ static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
* just fail them with EINVAL.
*/
if (page_address(page_array[i]) != page_addr)
- goto err;
+ goto free_pages;
page_addr += PAGE_SIZE;
}

*pages = page_array;
*npages = nr_pages;
return page_to_virt(page_array[0]);
+
+free_pages:
+ io_pages_free(&page_array, pinned > 0 ? pinned : 0);
+ return ERR_PTR(ret);
}

static void *io_rings_map(struct io_ring_ctx *ctx, unsigned long uaddr,
--
2.43.0