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[95.116.140.169]) by smtp.gmail.com with ESMTPSA id hu7sm172135ejc.62.2021.12.09.08.49.44 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Dec 2021 08:49:44 -0800 (PST) From: =?utf-8?q?Christian_G=C3=B6ttsche?= To: selinux@vger.kernel.org Subject: [PATCH v3 15/36] libsepol: zero member before potential dereference Date: Thu, 9 Dec 2021 17:49:07 +0100 Message-Id: <20211209164928.87459-16-cgzones@googlemail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211209164928.87459-1-cgzones@googlemail.com> References: <20211105154542.38434-1-cgzones@googlemail.com> <20211209164928.87459-1-cgzones@googlemail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org The `next` member might be checked against NULL and dereferenced before it gets assigned, due to jumps from failure gotos to the cleanup section. ==31017==ERROR: AddressSanitizer: SEGV on unknown address (pc 0x000000579654 bp 0x7ffd3a07d110 sp 0x7ffd3a07d000 T0) ==31017==The signal is caused by a READ memory access. ==31017==Hint: this fault was caused by a dereference of a high value address (see register values below). Disassemble the provided pc to learn which register was used. #0 0x579654 in filename_trans_read_one ./libsepol/src/policydb.c:2874:55 #1 0x579654 in filename_trans_read ./libsepol/src/policydb.c:2902:9 #2 0x5771b7 in policydb_read ./libsepol/src/policydb.c:4509:7 #3 0x55a1f5 in LLVMFuzzerTestOneInput ./libsepol/fuzz/binpolicy-fuzzer.c:24:6 #4 0x45aed3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) fuzzer.o #5 0x446a12 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) fuzzer.o #6 0x44c93b in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) fuzzer.o #7 0x475dd2 in main (./out/binpolicy-fuzzer+0x475dd2) #8 0x7f2a4e7f97ec in __libc_start_main csu/../csu/libc-start.c:332:16 #9 0x423689 in _start (./out/binpolicy-fuzzer+0x423689) Signed-off-by: Christian Göttsche --- libsepol/src/policydb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c index 25ffa07c..79aba3af 100644 --- a/libsepol/src/policydb.c +++ b/libsepol/src/policydb.c @@ -2780,6 +2780,7 @@ static int filename_trans_read_one(policydb_t *p, struct policy_file *fp) if (!datum) goto err; + datum->next = NULL; *dst = datum; /* ebitmap_read() will at least init the bitmap */ @@ -2797,7 +2798,6 @@ static int filename_trans_read_one(policydb_t *p, struct policy_file *fp) dst = &datum->next; } - *dst = NULL; if (ndatum > 1 && filename_trans_check_datum(first)) goto err;