From 329eaf9bae314f8bc307c809340b262f67c2ce36 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Svensson?= Date: Thu, 1 Sep 2022 13:47:54 +0200 Subject: [PATCH] Fix heap-buffer-overflow issue in redisvFormatCommad A command with a faulty formatting string that lacks the conversion specifier results in a ASAN heap-buffer-overflow. This was due to that strchr() matches on null-termination, which triggers a continuation of the string parsing. --- hiredis.c | 5 +++++ test.c | 6 +++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/hiredis.c b/hiredis.c index 1fd8570..6c48d66 100644 --- a/hiredis.c +++ b/hiredis.c @@ -402,6 +402,11 @@ int redisvFormatCommand(char **target, const char *format, va_list ap) { /* Copy va_list before consuming with va_arg */ va_copy(_cpy,ap); + /* Make sure we have more characters otherwise strchr() accepts + * '\0' as an integer specifier. This is checked after above + * va_copy() to avoid UB in fmt_invalid's call to va_end(). */ + if (*_p == '\0') goto fmt_invalid; + /* Integer conversion (without modifiers) */ if (strchr(intfmts,*_p) != NULL) { va_arg(ap,int); diff --git a/test.c b/test.c index 7d3e70a..e4aad54 100644 --- a/test.c +++ b/test.c @@ -339,10 +339,14 @@ static void test_format_commands(void) { FLOAT_WIDTH_TEST(float); FLOAT_WIDTH_TEST(double); - test("Format command with invalid printf format: "); + test("Format command with unhandled printf format (specifier 'p' not supported): "); len = redisFormatCommand(&cmd,"key:%08p %b",(void*)1234,"foo",(size_t)3); test_cond(len == -1); + test("Format command with invalid printf format (specifier missing): "); + len = redisFormatCommand(&cmd,"%-"); + test_cond(len == -1); + const char *argv[3]; argv[0] = "SET"; argv[1] = "foo\0xxx";