Commit-ID: d8e92de8ef952bed88c56c7a44c02d8dcae0984e Gitweb: https://git.kernel.org/tip/d8e92de8ef952bed88c56c7a44c02d8dcae0984e Author: Dominik Brodowski <li...@dominikbrodowski.net> AuthorDate: Sun, 11 Feb 2018 21:59:24 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 13 Feb 2018 09:04:56 +0100
selftests/x86: Clean up and document sscanf() usage Replace a couple of magically connected buffer length literal constants with a common definition that makes their relationship obvious. Also document why our sscanf() usage is safe. No intended functional changes. Suggested-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net> Cc: Andrew Lutomirski <l...@kernel.org> Cc: Andy Lutomirski <l...@kernel.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-kselft...@vger.kernel.org Cc: sh...@kernel.org Link: http://lkml.kernel.org/r/20180211205924.ga23...@light.dominikbrodowski.net Signed-off-by: Ingo Molnar <mi...@kernel.org> --- tools/testing/selftests/x86/test_vdso.c | 11 ++++++++--- tools/testing/selftests/x86/test_vsyscall.c | 11 ++++++++--- 2 files changed, 16 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/x86/test_vdso.c b/tools/testing/selftests/x86/test_vdso.c index 558c820..2352590 100644 --- a/tools/testing/selftests/x86/test_vdso.c +++ b/tools/testing/selftests/x86/test_vdso.c @@ -26,6 +26,9 @@ # endif #endif +/* max length of lines in /proc/self/maps - anything longer is skipped here */ +#define MAPS_LINE_LEN 128 + int nerrs = 0; typedef long (*getcpu_t)(unsigned *, unsigned *, void *); @@ -37,17 +40,19 @@ static void *vsyscall_getcpu(void) { #ifdef __x86_64__ FILE *maps; - char line[128]; + char line[MAPS_LINE_LEN]; bool found = false; maps = fopen("/proc/self/maps", "r"); if (!maps) /* might still be present, but ignore it here, as we test vDSO not vsyscall */ return NULL; - while (fgets(line, sizeof(line), maps)) { + while (fgets(line, MAPS_LINE_LEN, maps)) { char r, x; void *start, *end; - char name[128]; + char name[MAPS_LINE_LEN]; + + /* sscanf() is safe here as strlen(name) >= strlen(line) */ if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s", &start, &end, &r, &x, name) != 5) continue; diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c index 7a744fa..be81621 100644 --- a/tools/testing/selftests/x86/test_vsyscall.c +++ b/tools/testing/selftests/x86/test_vsyscall.c @@ -33,6 +33,9 @@ # endif #endif +/* max length of lines in /proc/self/maps - anything longer is skipped here */ +#define MAPS_LINE_LEN 128 + static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags) { @@ -98,7 +101,7 @@ static int init_vsys(void) #ifdef __x86_64__ int nerrs = 0; FILE *maps; - char line[128]; + char line[MAPS_LINE_LEN]; bool found = false; maps = fopen("/proc/self/maps", "r"); @@ -108,10 +111,12 @@ static int init_vsys(void) return 0; } - while (fgets(line, sizeof(line), maps)) { + while (fgets(line, MAPS_LINE_LEN, maps)) { char r, x; void *start, *end; - char name[128]; + char name[MAPS_LINE_LEN]; + + /* sscanf() is safe here as strlen(name) >= strlen(line) */ if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s", &start, &end, &r, &x, name) != 5) continue;
