From 9b1268f55ceb0d9390a051cad299b3021dfa9896 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 25 Jul 2022 15:05:16 +0100 Subject: [PATCH] semihosting: Fix handling of buffer in TARGET_SYS_TMPNAM MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The TARGET_SYS_TMPNAM implementation has two bugs spotted by Coverity: * confusion about whether 'len' has the length of the string including or excluding the terminating NUL means we lock_user() len bytes of memory but memcpy() len + 1 bytes * In the error-exit cases we forget to free() the buffer that asprintf() returned to us Resolves: Coverity CID 1490285, 1490289 Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-Id: <20220719121110.225657-5-peter.maydell@linaro.org> Signed-off-by: Alex Bennée Message-Id: <20220725140520.515340-10-alex.bennee@linaro.org> --- semihosting/arm-compat-semi.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/semihosting/arm-compat-semi.c b/semihosting/arm-compat-semi.c index d12288fc80..e741674238 100644 --- a/semihosting/arm-compat-semi.c +++ b/semihosting/arm-compat-semi.c @@ -504,16 +504,25 @@ void do_common_semihosting(CPUState *cs) GET_ARG(1); GET_ARG(2); len = asprintf(&s, "/tmp/qemu-%x%02x", getpid(), (int)arg1 & 0xff); + if (len < 0) { + common_semi_set_ret(cs, -1); + break; + } + + /* Allow for trailing NUL */ + len++; /* Make sure there's enough space in the buffer */ - if (len < 0 || len >= arg2) { + if (len > arg2) { + free(s); common_semi_set_ret(cs, -1); break; } p = lock_user(VERIFY_WRITE, arg0, len, 0); if (!p) { + free(s); goto do_fault; } - memcpy(p, s, len + 1); + memcpy(p, s, len); unlock_user(p, arg0, len); free(s); common_semi_set_ret(cs, 0);