From f169afd188e3765d0a4d39c79ff8d0aff4d5f8a7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= Date: Thu, 7 Oct 2021 15:29:51 +0200 Subject: [PATCH] libsepol: add checks for read sizes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add checks for invalid read sizes from a binary policy to guard allocations. In the fuzzer build the value will also be bounded to avoid oom reports. ==29857== ERROR: libFuzzer: out-of-memory (malloc(17179868160)) To change the out-of-memory limit use -rss_limit_mb= #0 0x52dc61 in __sanitizer_print_stack_trace (./out/binpolicy-fuzzer+0x52dc61) #1 0x475618 in fuzzer::PrintStackTrace() fuzzer.o #2 0x458855 in fuzzer::Fuzzer::HandleMalloc(unsigned long) fuzzer.o #3 0x45876a in fuzzer::MallocHook(void const volatile*, unsigned long) fuzzer.o #4 0x534557 in __sanitizer::RunMallocHooks(void const*, unsigned long) (./out/binpolicy-fuzzer+0x534557) #5 0x4aa7d7 in __asan::Allocator::Allocate(unsigned long, unsigned long, __sanitizer::BufferedStackTrace*, __asan::AllocType, bool) (./out/binpolicy-fuzzer+0x4aa7d7) #6 0x4aa143 in __asan::asan_malloc(unsigned long, __sanitizer::BufferedStackTrace*) (./out/binpolicy-fuzzer+0x4aa143) #7 0x5259cb in malloc (./out/binpolicy-fuzzer+0x5259cb) #8 0x580b5d in mallocarray ./libsepol/src/./private.h:93:9 #9 0x57c2ed in scope_read ./libsepol/src/policydb.c:4120:7 #10 0x576b0d in policydb_read ./libsepol/src/policydb.c:4462:9 #11 0x55a214 in LLVMFuzzerTestOneInput ./libsepol/fuzz/binpolicy-fuzzer.c:26:6 #12 0x45aed3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) fuzzer.o #13 0x446a12 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) fuzzer.o #14 0x44c93b in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) fuzzer.o #15 0x475dd2 in main (./out/binpolicy-fuzzer+0x475dd2) #16 0x7ffad6e107ec in __libc_start_main csu/../csu/libc-start.c:332:16 #17 0x423689 in _start (./out/binpolicy-fuzzer+0x423689) ==19462== ERROR: libFuzzer: out-of-memory (malloc(18253611008)) To change the out-of-memory limit use -rss_limit_mb= #0 0x52dc61 in __sanitizer_print_stack_trace (./out/binpolicy-fuzzer+0x52dc61) #1 0x475618 in fuzzer::PrintStackTrace() fuzzer.o #2 0x458855 in fuzzer::Fuzzer::HandleMalloc(unsigned long) fuzzer.o #3 0x45876a in fuzzer::MallocHook(void const volatile*, unsigned long) fuzzer.o #4 0x534557 in __sanitizer::RunMallocHooks(void const*, unsigned long) (./out/binpolicy-fuzzer+0x534557) #5 0x4aa7d7 in __asan::Allocator::Allocate(unsigned long, unsigned long, __sanitizer::BufferedStackTrace*, __asan::AllocType, bool) (./out/binpolicy-fuzzer+0x4aa7d7) #6 0x4aa999 in __asan::asan_calloc(unsigned long, unsigned long, __sanitizer::BufferedStackTrace*) (./out/binpolicy-fuzzer+0x4aa999) #7 0x525b63 in __interceptor_calloc (./out/binpolicy-fuzzer+0x525b63) #8 0x570938 in policydb_index_others ./libsepol/src/policydb.c:1245:6 #9 0x5771f3 in policydb_read ./src/policydb.c:4481:6 #10 0x55a214 in LLVMFuzzerTestOneInput ./libsepol/fuzz/binpolicy-fuzzer.c:26:6 #11 0x45aed3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) fuzzer.o #12 0x446a12 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) fuzzer.o #13 0x44c93b in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) fuzzer.o #14 0x475dd2 in main (./out/binpolicy-fuzzer+0x475dd2) #15 0x7f4d933157ec in __libc_start_main csu/../csu/libc-start.c:332:16 #16 0x423689 in _start (./out/binpolicy-fuzzer+0x423689) Signed-off-by: Christian Göttsche --- libsepol/src/policydb.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c index 46fb48930a..70b503e1b6 100644 --- a/libsepol/src/policydb.c +++ b/libsepol/src/policydb.c @@ -2103,6 +2103,8 @@ static int common_read(policydb_t * p, hashtab_t h, struct policy_file *fp) if (symtab_init(&comdatum->permissions, PERM_SYMTAB_SIZE)) goto bad; comdatum->permissions.nprim = le32_to_cpu(buf[2]); + if (is_saturated(comdatum->permissions.nprim)) + goto bad; nel = le32_to_cpu(buf[3]); key = malloc(len + 1); @@ -2251,6 +2253,8 @@ static int class_read(policydb_t * p, hashtab_t h, struct policy_file *fp) if (symtab_init(&cladatum->permissions, PERM_SYMTAB_SIZE)) goto bad; cladatum->permissions.nprim = le32_to_cpu(buf[3]); + if (is_saturated(cladatum->permissions.nprim)) + goto bad; nel = le32_to_cpu(buf[4]); ncons = le32_to_cpu(buf[5]); @@ -3980,6 +3984,8 @@ static int avrule_decl_read(policydb_t * p, avrule_decl_t * decl, if (rc < 0) return -1; nprim = le32_to_cpu(buf[0]); + if (is_saturated(nprim)) + return -1; nel = le32_to_cpu(buf[1]); for (j = 0; j < nel; j++) { if (read_f[i] (p, decl->symtab[i].table, fp)) { @@ -4106,7 +4112,7 @@ static int scope_read(policydb_t * p, int symnum, struct policy_file *fp) goto cleanup; scope->scope = le32_to_cpu(buf[0]); scope->decl_ids_len = le32_to_cpu(buf[1]); - if (scope->decl_ids_len == 0) { + if (zero_or_saturated(scope->decl_ids_len)) { ERR(fp->handle, "invalid scope with no declaration"); goto cleanup; } @@ -4396,6 +4402,8 @@ int policydb_read(policydb_t * p, struct policy_file *fp, unsigned verbose) if (rc < 0) goto bad; nprim = le32_to_cpu(buf[0]); + if (is_saturated(nprim)) + goto bad; nel = le32_to_cpu(buf[1]); if (nel && !nprim) { ERR(fp->handle, "unexpected items in symbol table with no symbol");