From: Douglas Gilbert dgilbert@interlog.com
stable inclusion from linux-4.19.155 commit e6786fd18fe2b91a4844f7d1606c50e09d4cebcf
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[ 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 Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- lib/scatterlist.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/scatterlist.c b/lib/scatterlist.c index 60e7eca2f4be..3b859201f84c 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -506,7 +506,7 @@ 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; }