From f91f7ac900e7342e0fd66093dfbf7cb8cb585a99 Mon Sep 17 00:00:00 2001 From: Petr Pavlu Date: Wed, 17 Jul 2024 15:00:23 +0200 Subject: refcount: Report UAF for refcount_sub_and_test(0) when counter==0 When a reference counter is at zero and refcount_sub_and_test() is invoked to subtract zero, the function accepts this request without any warning and returns true. This behavior does not seem ideal because the counter being already at zero indicates a use-after-free. Furthermore, returning true by refcount_sub_and_test() in this case potentially results in a double-free done by its caller. Modify the underlying function __refcount_sub_and_test() to warn about this case as a use-after-free and have it return false to avoid the potential double-free. Signed-off-by: Petr Pavlu Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240717130023.5675-1-petr.pavlu@suse.com Signed-off-by: Kees Cook --- drivers/misc/lkdtm/refcount.c | 16 ++++++++++++++++ include/linux/refcount.h | 4 ++-- 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/misc/lkdtm/refcount.c b/drivers/misc/lkdtm/refcount.c index 5cd488f54cfa..8f744bee6fbd 100644 --- a/drivers/misc/lkdtm/refcount.c +++ b/drivers/misc/lkdtm/refcount.c @@ -182,6 +182,21 @@ static void lkdtm_REFCOUNT_SUB_AND_TEST_NEGATIVE(void) check_negative(&neg, 3); } +/* + * A refcount_sub_and_test() by zero when the counter is at zero should act like + * refcount_sub_and_test() above when going negative. + */ +static void lkdtm_REFCOUNT_SUB_AND_TEST_ZERO(void) +{ + refcount_t neg = REFCOUNT_INIT(0); + + pr_info("attempting bad refcount_sub_and_test() at zero\n"); + if (refcount_sub_and_test(0, &neg)) + pr_warn("Weird: refcount_sub_and_test() reported zero\n"); + + check_negative(&neg, 0); +} + static void check_from_zero(refcount_t *ref) { switch (refcount_read(ref)) { @@ -400,6 +415,7 @@ static struct crashtype crashtypes[] = { CRASHTYPE(REFCOUNT_DEC_NEGATIVE), CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE), CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE), + CRASHTYPE(REFCOUNT_SUB_AND_TEST_ZERO), CRASHTYPE(REFCOUNT_INC_ZERO), CRASHTYPE(REFCOUNT_ADD_ZERO), CRASHTYPE(REFCOUNT_INC_SATURATED), diff --git a/include/linux/refcount.h b/include/linux/refcount.h index 59b3b752394d..35f039ecb272 100644 --- a/include/linux/refcount.h +++ b/include/linux/refcount.h @@ -266,12 +266,12 @@ bool __refcount_sub_and_test(int i, refcount_t *r, int *oldp) if (oldp) *oldp = old; - if (old == i) { + if (old > 0 && old == i) { smp_acquire__after_ctrl_dep(); return true; } - if (unlikely(old < 0 || old - i < 0)) + if (unlikely(old <= 0 || old - i < 0)) refcount_warn_saturate(r, REFCOUNT_SUB_UAF); return false; -- cgit From f32e90c0688a3d1f8079ac18ed39b752d22e92bd Mon Sep 17 00:00:00 2001 From: Thorsten Blum Date: Tue, 23 Jul 2024 18:53:31 +0200 Subject: gcc-plugins: randstruct: Remove GCC 4.7 or newer requirement Since the kernel currently requires GCC 5.1 as a minimum, remove the unnecessary GCC version >= 4.7 check. Signed-off-by: Thorsten Blum Link: https://lore.kernel.org/r/20240723165332.1947-1-thorsten.blum@toblux.com Signed-off-by: Kees Cook --- scripts/gcc-plugins/randomize_layout_plugin.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c index 746ff2d272f2..5694df3da2e9 100644 --- a/scripts/gcc-plugins/randomize_layout_plugin.c +++ b/scripts/gcc-plugins/randomize_layout_plugin.c @@ -19,10 +19,6 @@ #include "gcc-common.h" #include "randomize_layout_seed.h" -#if BUILDING_GCC_MAJOR < 4 || (BUILDING_GCC_MAJOR == 4 && BUILDING_GCC_MINOR < 7) -#error "The RANDSTRUCT plugin requires GCC 4.7 or newer." -#endif - #define ORIG_TYPE_NAME(node) \ (TYPE_NAME(TYPE_MAIN_VARIANT(node)) != NULL_TREE ? ((const unsigned char *)IDENTIFIER_POINTER(TYPE_NAME(TYPE_MAIN_VARIANT(node)))) : (const unsigned char *)"anonymous") -- cgit From 92e9bac18124682c4b99ede9ee3bcdd68f121e92 Mon Sep 17 00:00:00 2001 From: Ivan Orlov Date: Thu, 15 Aug 2024 01:04:31 +0100 Subject: kunit/overflow: Fix UB in overflow_allocation_test The 'device_name' array doesn't exist out of the 'overflow_allocation_test' function scope. However, it is being used as a driver name when calling 'kunit_driver_create' from 'kunit_device_register'. It produces the kernel panic with KASAN enabled. Since this variable is used in one place only, remove it and pass the device name into kunit_device_register directly as an ascii string. Signed-off-by: Ivan Orlov Reviewed-by: David Gow Link: https://lore.kernel.org/r/20240815000431.401869-1-ivan.orlov0322@gmail.com Signed-off-by: Kees Cook --- lib/overflow_kunit.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c index f314a0c15a6d..2abc78367dd1 100644 --- a/lib/overflow_kunit.c +++ b/lib/overflow_kunit.c @@ -668,7 +668,6 @@ DEFINE_TEST_ALLOC(devm_kzalloc, devm_kfree, 1, 1, 0); static void overflow_allocation_test(struct kunit *test) { - const char device_name[] = "overflow-test"; struct device *dev; int count = 0; @@ -678,7 +677,7 @@ static void overflow_allocation_test(struct kunit *test) } while (0) /* Create dummy device for devm_kmalloc()-family tests. */ - dev = kunit_device_register(test, device_name); + dev = kunit_device_register(test, "overflow-test"); KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev), "Cannot register test device\n"); -- cgit From 020925ce92990c3bf59ab2cde386ac6d9ec734ff Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 7 Aug 2024 15:05:12 -0700 Subject: kallsyms: Do not cleanup .llvm. suffix before sorting symbols Cleaning up the symbols causes various issues afterwards. Let's sort the list based on original name. Signed-off-by: Song Liu Fixes: 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes from promoted global functions") Reviewed-by: Masami Hiramatsu (Google) Tested-by: Masami Hiramatsu (Google) Acked-by: Petr Mladek Reviewed-by: Sami Tolvanen Reviewed-by: Luis Chamberlain Link: https://lore.kernel.org/r/20240807220513.3100483-2-song@kernel.org Signed-off-by: Kees Cook --- scripts/kallsyms.c | 31 ++----------------------------- scripts/link-vmlinux.sh | 4 ---- 2 files changed, 2 insertions(+), 33 deletions(-) diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 0ed873491bf5..123dab0572f8 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -5,8 +5,7 @@ * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. * - * Usage: kallsyms [--all-symbols] [--absolute-percpu] - * [--lto-clang] in.map > out.S + * Usage: kallsyms [--all-symbols] [--absolute-percpu] in.map > out.S * * Table compression uses all the unused char codes on the symbols and * maps these to the most used substrings (tokens). For instance, it might @@ -62,7 +61,6 @@ static struct sym_entry **table; static unsigned int table_size, table_cnt; static int all_symbols; static int absolute_percpu; -static int lto_clang; static int token_profit[0x10000]; @@ -73,8 +71,7 @@ static unsigned char best_table_len[256]; static void usage(void) { - fprintf(stderr, "Usage: kallsyms [--all-symbols] [--absolute-percpu] " - "[--lto-clang] in.map > out.S\n"); + fprintf(stderr, "Usage: kallsyms [--all-symbols] [--absolute-percpu] in.map > out.S\n"); exit(1); } @@ -344,25 +341,6 @@ static bool symbol_absolute(const struct sym_entry *s) return s->percpu_absolute; } -static void cleanup_symbol_name(char *s) -{ - char *p; - - /* - * ASCII[.] = 2e - * ASCII[0-9] = 30,39 - * ASCII[A-Z] = 41,5a - * ASCII[_] = 5f - * ASCII[a-z] = 61,7a - * - * As above, replacing the first '.' in ".llvm." with '\0' does not - * affect the main sorting, but it helps us with subsorting. - */ - p = strstr(s, ".llvm."); - if (p) - *p = '\0'; -} - static int compare_names(const void *a, const void *b) { int ret; @@ -526,10 +504,6 @@ static void write_src(void) output_address(relative_base); printf("\n"); - if (lto_clang) - for (i = 0; i < table_cnt; i++) - cleanup_symbol_name((char *)table[i]->sym); - sort_symbols_by_name(); output_label("kallsyms_seqs_of_names"); for (i = 0; i < table_cnt; i++) @@ -807,7 +781,6 @@ int main(int argc, char **argv) static const struct option long_options[] = { {"all-symbols", no_argument, &all_symbols, 1}, {"absolute-percpu", no_argument, &absolute_percpu, 1}, - {"lto-clang", no_argument, <o_clang, 1}, {}, }; diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index f7b2503cdba9..22d0bc843986 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -156,10 +156,6 @@ kallsyms() kallsymopt="${kallsymopt} --absolute-percpu" fi - if is_enabled CONFIG_LTO_CLANG; then - kallsymopt="${kallsymopt} --lto-clang" - fi - info KSYMS "${2}.S" scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" -- cgit From fb6a421fb6153d97cf3058f9bd550b377b76a490 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Wed, 7 Aug 2024 15:05:13 -0700 Subject: kallsyms: Match symbols exactly with CONFIG_LTO_CLANG With CONFIG_LTO_CLANG=y, the compiler may add .llvm. suffix to function names to avoid duplication. APIs like kallsyms_lookup_name() and kallsyms_on_each_match_symbol() tries to match these symbol names without the .llvm. suffix, e.g., match "c_stop" with symbol c_stop.llvm.17132674095431275852. This turned out to be problematic for use cases that require exact match, for example, livepatch. Fix this by making the APIs to match symbols exactly. Also cleanup kallsyms_selftests accordingly. Signed-off-by: Song Liu Fixes: 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes from promoted global functions") Tested-by: Masami Hiramatsu (Google) Reviewed-by: Masami Hiramatsu (Google) Acked-by: Petr Mladek Reviewed-by: Sami Tolvanen Reviewed-by: Luis Chamberlain Link: https://lore.kernel.org/r/20240807220513.3100483-3-song@kernel.org Signed-off-by: Kees Cook --- kernel/kallsyms.c | 55 +++++----------------------------------------- kernel/kallsyms_selftest.c | 22 +------------------ 2 files changed, 7 insertions(+), 70 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index fb2c77368d18..a9a0ca605d4a 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -160,38 +160,6 @@ unsigned long kallsyms_sym_address(int idx) return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; } -static void cleanup_symbol_name(char *s) -{ - char *res; - - if (!IS_ENABLED(CONFIG_LTO_CLANG)) - return; - - /* - * LLVM appends various suffixes for local functions and variables that - * must be promoted to global scope as part of LTO. This can break - * hooking of static functions with kprobes. '.' is not a valid - * character in an identifier in C. Suffixes only in LLVM LTO observed: - * - foo.llvm.[0-9a-f]+ - */ - res = strstr(s, ".llvm."); - if (res) - *res = '\0'; - - return; -} - -static int compare_symbol_name(const char *name, char *namebuf) -{ - /* The kallsyms_seqs_of_names is sorted based on names after - * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled. - * To ensure correct bisection in kallsyms_lookup_names(), do - * cleanup_symbol_name(namebuf) before comparing name and namebuf. - */ - cleanup_symbol_name(namebuf); - return strcmp(name, namebuf); -} - static unsigned int get_symbol_seq(int index) { unsigned int i, seq = 0; @@ -219,7 +187,7 @@ static int kallsyms_lookup_names(const char *name, seq = get_symbol_seq(mid); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); - ret = compare_symbol_name(name, namebuf); + ret = strcmp(name, namebuf); if (ret > 0) low = mid + 1; else if (ret < 0) @@ -236,7 +204,7 @@ static int kallsyms_lookup_names(const char *name, seq = get_symbol_seq(low - 1); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); - if (compare_symbol_name(name, namebuf)) + if (strcmp(name, namebuf)) break; low--; } @@ -248,7 +216,7 @@ static int kallsyms_lookup_names(const char *name, seq = get_symbol_seq(high + 1); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); - if (compare_symbol_name(name, namebuf)) + if (strcmp(name, namebuf)) break; high++; } @@ -407,8 +375,7 @@ static int kallsyms_lookup_buildid(unsigned long addr, if (modbuildid) *modbuildid = NULL; - ret = strlen(namebuf); - goto found; + return strlen(namebuf); } /* See if it's in a module or a BPF JITed image. */ @@ -422,8 +389,6 @@ static int kallsyms_lookup_buildid(unsigned long addr, ret = ftrace_mod_address_lookup(addr, symbolsize, offset, modname, namebuf); -found: - cleanup_symbol_name(namebuf); return ret; } @@ -450,8 +415,6 @@ const char *kallsyms_lookup(unsigned long addr, int lookup_symbol_name(unsigned long addr, char *symname) { - int res; - symname[0] = '\0'; symname[KSYM_NAME_LEN - 1] = '\0'; @@ -462,16 +425,10 @@ int lookup_symbol_name(unsigned long addr, char *symname) /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), symname, KSYM_NAME_LEN); - goto found; + return 0; } /* See if it's in a module. */ - res = lookup_module_symbol_name(addr, symname); - if (res) - return res; - -found: - cleanup_symbol_name(symname); - return 0; + return lookup_module_symbol_name(addr, symname); } /* Look up a kernel symbol and return it in a text buffer. */ diff --git a/kernel/kallsyms_selftest.c b/kernel/kallsyms_selftest.c index 2f84896a7bcb..873f7c445488 100644 --- a/kernel/kallsyms_selftest.c +++ b/kernel/kallsyms_selftest.c @@ -187,31 +187,11 @@ static void test_perf_kallsyms_lookup_name(void) stat.min, stat.max, div_u64(stat.sum, stat.real_cnt)); } -static bool match_cleanup_name(const char *s, const char *name) -{ - char *p; - int len; - - if (!IS_ENABLED(CONFIG_LTO_CLANG)) - return false; - - p = strstr(s, ".llvm."); - if (!p) - return false; - - len = strlen(name); - if (p - s != len) - return false; - - return !strncmp(s, name, len); -} - static int find_symbol(void *data, const char *name, unsigned long addr) { struct test_stat *stat = (struct test_stat *)data; - if (strcmp(name, stat->name) == 0 || - (!stat->perf && match_cleanup_name(name, stat->name))) { + if (!strcmp(name, stat->name)) { stat->real_cnt++; stat->addr = addr; -- cgit