[PATCH 4.14 059/125] sgl_alloc_order: fix memory leak

Greg Kroah-Hartman
2020-11-03T21:16:47Z

From: Douglas Gilbert <dgilbert@interlog.com>

[ Upstream commit b2a182a40278bc5849730e66bca01a762188ed86 ]

sgl_alloc_order() can fail when 'length' is large on a memory
constrained system. When order > 0 it will potentially be
making several multi-page allocations with the later ones more
likely to fail than the earlier one. So it is important that
sgl_alloc_order() frees up any pages it has obtained before
returning NULL. In the case when order > 0 it calls the wrong
free page function and leaks. In testing the leak was
sufficient to bring down my 8 GiB laptop with OOM.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/scatterlist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 834c846c5af84..2cf02a82d502b 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -477,7 +477,7 @@ struct scatterlist *sgl_alloc_order(unsigned long long length,
elem_len = min_t(u64, length, PAGE_SIZE << order);
page = alloc_pages(gfp, order);
if (!page) {
- sgl_free(sgl);
+ sgl_free_order(sgl, order);
return NULL;
}

--
2.27.0