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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id t8-20020a1709027fc800b00186c37270f6sm4294533plb.24.2022.11.18.15.23.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Nov 2022 15:23:53 -0800 (PST) From: Kees Cook To: Jaroslav Kysela Cc: Kees Cook , kernel test robot , Takashi Iwai , "Gustavo A. R. Silva" , alsa-devel@alsa-project.org, Nathan Chancellor , Nick Desaulniers , Tom Rix , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-hardening@vger.kernel.org Subject: [PATCH] ALSA: seq: Fix function prototype mismatch in snd_seq_expand_var_event Date: Fri, 18 Nov 2022 15:23:50 -0800 Message-Id: <20221118232346.never.380-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2388; h=from:subject:message-id; bh=LT8LvayoodyeGcJJmotl0W7abaTXyRbApRilntoVIaM=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjeBQGxl97XSZ/V131zxWG6VCVlDXD5V6MNXIDGf3M dU2HgY2JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCY3gUBgAKCRCJcvTf3G3AJpNYD/ 970LXJu9T/r8J1MdqoqIR+muUaph3v/3r/JnVdIrugZjYUdZroQAGmvpKjF0NaevA5Rz+pYN8ejlBj QCPPFn5ld4zzw7miWLwRD05VvEonWs3fDK6yDqlRABnzMMa9TT0lLFvtxsLxoBMT5s9qf//qz59Q4C kJlTlPyMuRoTP6U3rbnw5ZbjkL1XWiQCUtIds/ZuIZk+lZU8qDtP0jBWfl2GpVsvXReyulyp7AkqbL pv+uGEb/ka/nhxaU7+4bse+EhIbJZ6d4hfuwkwjv6eAgbXjPV0cNc6D9/dKU2W7cvi6bD6bwwY9Z1F kHfxdJvYbQ+B+MTlG3O2mqN22daWBExivwMVg0gqOIyyUle1c4UceAT9IPZXOO5Ytvb3sHAdi3FySz riUxg7OnQoqX4ZuaEAiRtaeIKXp71OaAM2dSFQfZBwB0EkiG+fC5uN3Cs4g0nRt+irHwt1KKCnF/I9 owyMxTCpvATaqHdA3h+cfpn9xjWayAWEFTkd1duwlgCx9gT72iAKCzpDSaVEY1pzHHI+Ln3obru+it k9bsAVVu6S6l/VCU9Ul5sP6yxcHNx/SCeproJkeKDuNgk42tk8FP0RNs9P4BNVvqwszpuwfSwHuLqM exJ4TGIXwDqUUOs4vVncpMokhUYJqkBaLE55d9yYRqhWomued0koClDyDE1A== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. seq_copy_in_user() and seq_copy_in_kernel() did not have prototypes matching snd_seq_dump_func_t. Adjust this and remove the casts. There are not resulting binary output differences. This was found as a result of Clang's new -Wcast-function-type-strict flag, which is more sensitive than the simpler -Wcast-function-type, which only checks for type width mismatches. Reported-by: kernel test robot Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: "Gustavo A. R. Silva" Cc: alsa-devel@alsa-project.org Signed-off-by: Kees Cook --- sound/core/seq/seq_memory.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/sound/core/seq/seq_memory.c b/sound/core/seq/seq_memory.c index b7aee23fc387..47ef6bc30c0e 100644 --- a/sound/core/seq/seq_memory.c +++ b/sound/core/seq/seq_memory.c @@ -113,15 +113,19 @@ EXPORT_SYMBOL(snd_seq_dump_var_event); * expand the variable length event to linear buffer space. */ -static int seq_copy_in_kernel(char **bufptr, const void *src, int size) +static int seq_copy_in_kernel(void *ptr, void *src, int size) { + char **bufptr = ptr; + memcpy(*bufptr, src, size); *bufptr += size; return 0; } -static int seq_copy_in_user(char __user **bufptr, const void *src, int size) +static int seq_copy_in_user(void *ptr, void *src, int size) { + char __user **bufptr = ptr; + if (copy_to_user(*bufptr, src, size)) return -EFAULT; *bufptr += size; @@ -151,8 +155,7 @@ int snd_seq_expand_var_event(const struct snd_seq_event *event, int count, char return newlen; } err = snd_seq_dump_var_event(event, - in_kernel ? (snd_seq_dump_func_t)seq_copy_in_kernel : - (snd_seq_dump_func_t)seq_copy_in_user, + in_kernel ? seq_copy_in_kernel : seq_copy_in_user, &buf); return err < 0 ? err : newlen; } -- 2.34.1