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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id h10-20020a170902680a00b0017300ec80b0sm8058997plk.308.2022.10.18.02.10.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Oct 2022 02:10:13 -0700 (PDT) From: Kees Cook To: Sumit Semwal Cc: Kees Cook , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?utf-8?q?Christian_K=C3=B6nig?= , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v3] dma-buf: Proactively round up to kmalloc bucket size Date: Tue, 18 Oct 2022 02:10:11 -0700 Message-Id: <20221018090858.never.941-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1673; h=from:subject:message-id; bh=8hepCmu6KkNCIQiT6ONpaMe4VoHSy9sRDnadRc3o6dY=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjTm1zq8jKCG/tc7/8bPvsM44d+bw8pliNmUV1nYs9 oZ3UNCqJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCY05tcwAKCRCJcvTf3G3AJh7AEA CTcI1pdlR5PlvYxNvP2WDxxU4tjQpCYFU8DL3QIbpSPAGCSHnu/fLH6mOTmflitrQ/DsyHD4LRh+Gc MNL44FREEbJ4PDUi+k2SbLlkCESNKduXwzMSU4AzBIbf3TD2GmvqnQc6663oVj/0gCMK1PtcnYqkkK 7dOrQHMvouIoxWrgiOoK8U8K+6pHwwJK66vChECKJN261DcRu+LrteWxTMCEuwWexFa8DVde3NAK9Z rBLz4Cq8ZdLitk/OXx0Dq5Sr+lvsTuhgodexasrD6PbK4g3XSSyHuqSiRLwSb+WgKJaOQ/FwHA/zxz N1ktC3FGVv0rs3PTxdAwcI0FNVEpUdZUkQI0UfFotI03jATt3Ar/11oa77oln6OVD4p86J25TmPSsL 5mbkclNofm6EXo/VniQoq6dc6Bt4acmroVMeYDxRuAwfwxW0tBusHyGG0uUaczhMLcI+8aB7B9Ww5w Z1tpDuQLaTSmDAfOskStapWlFTBdZczM8RsO88iM5k/TH/00g53wBnDEHyYBXaMZWIc+rSuGFChZzf H0+guk6+nfMF3k18/pY3Ysj5RPQE3FF4i1DOJ1aqc9zQLB9+BV8bbsTxy/GCHGenjhYmFipzHZeJat dOlM+mCyFQ3zOAYDS2ZW+1sW0Gfg5Xqh5qC7jyxMfqfwVjvzt1oaXABQEm0g== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Instead of discovering the kmalloc bucket size _after_ allocation, round up proactively so the allocation is explicitly made for the full size, allowing the compiler to correctly reason about the resulting size of the buffer through the existing __alloc_size() hint. Cc: Sumit Semwal Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Christian König Signed-off-by: Kees Cook --- v3: added reviewed-by, rebase to v6.1-rc1 v2: https://lore.kernel.org/lkml/20220923202822.2667581-9-keescook@chromium.org/ --- drivers/dma-buf/dma-resv.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index e3885c90a3ac..1c76aed8e262 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -98,12 +98,17 @@ static void dma_resv_list_set(struct dma_resv_list *list, static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences) { struct dma_resv_list *list; + size_t size; - list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL); + /* Round up to the next kmalloc bucket size. */ + size = kmalloc_size_roundup(struct_size(list, table, max_fences)); + + list = kmalloc(size, GFP_KERNEL); if (!list) return NULL; - list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) / + /* Given the resulting bucket size, recalculated max_fences. */ + list->max_fences = (size - offsetof(typeof(*list), table)) / sizeof(*list->table); return list;