Re: [PATCH v8 02/23] dma-pool: fix page leak in atomic_pool_expand() cleanup
From: Leon Romanovsky <leon@kernel.org>
Date: 2026-07-21 12:31:25
Also in:
linux-arm-kernel, linux-coco, linux-iommu, linux-s390, lkml
On Fri, Jul 17, 2026 at 11:34:20PM +0530, Aneesh Kumar K.V (Arm) wrote:
quoted hunk ↗ jump to hunk
atomic_pool_expand() frees the allocated pages from the remove_mapping error path only when CONFIG_DMA_DIRECT_REMAP is enabled. When CONFIG_DMA_DIRECT_REMAP is disabled, failures after page allocation, such as gen_pool_add_virt(), jump to remove_mapping and return without freeing the pages. Move __free_pages(page, order) out of the CONFIG_DMA_DIRECT_REMAP block so that cleanup paths always release the allocation. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Tested-by: Michael Kelley <redacted> Tested-by: Mostafa Saleh <smostafa@google.com> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org> --- kernel/dma/pool.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 2b2fbb709242..b0303efbc153 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c@@ -81,6 +81,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, { unsigned int order; struct page *page = NULL; + bool leak_pages = false; void *addr; int ret = -ENOMEM;@@ -115,8 +116,10 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, */ ret = set_memory_decrypted((unsigned long)page_to_virt(page), 1 << order); - if (ret) + if (ret) { + leak_pages = true; goto remove_mapping; + } ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page), pool_size, NUMA_NO_NODE); if (ret)@@ -130,14 +133,15 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, 1 << order); if (WARN_ON_ONCE(ret)) { /* Decrypt succeeded but encrypt failed, purposely leak */ - goto out; + leak_pages = true;
Instead of doing this dance with temporal variable, change "goto out" to be "return true".
} remove_mapping: #ifdef CONFIG_DMA_DIRECT_REMAP dma_common_free_remap(addr, pool_size); free_page:
Remove free_page label, and change leftover of "goto free_page" to be "goto out"
- __free_pages(page, order); #endif + if (!leak_pages) + __free_pages(page, order);
Put these checks under out label and rely on page != NULL as a marker. if (page) __free_pages(page, order);
out: return ret; } -- 2.43.0