Index: lib/sanitizer_common/sanitizer_common_interceptors.inc =================================================================== --- lib/sanitizer_common/sanitizer_common_interceptors.inc +++ lib/sanitizer_common/sanitizer_common_interceptors.inc @@ -5498,7 +5498,7 @@ COMMON_INTERCEPTOR_FD_ACCESS(ctx, fd); SSIZE_T res = REAL(recv)(fd, buf, len, flags); if (res > 0) { - COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, res); + COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, Min((SIZE_T)res, len)); } if (res >= 0 && fd >= 0) COMMON_INTERCEPTOR_FD_ACQUIRE(ctx, fd); return res; @@ -5515,7 +5515,7 @@ (void)srcaddr_sz; // prevent "set but not used" warning SSIZE_T res = REAL(recvfrom)(fd, buf, len, flags, srcaddr, addrlen); if (res > 0) { - COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, res); + COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, Min((SIZE_T)res, len)); if (srcaddr) COMMON_INTERCEPTOR_INITIALIZE_RANGE(srcaddr, Min((SIZE_T)*addrlen, srcaddr_sz)); Index: test/sanitizer_common/TestCases/Linux/recv_msg_trunc.cc =================================================================== --- /dev/null +++ test/sanitizer_common/TestCases/Linux/recv_msg_trunc.cc @@ -0,0 +1,36 @@ +// Test that ASan doesn't raise false alarm when MSG_TRUNC is present. +// +// RUN: %clangxx %s -o %t && %run %t 2>&1 +// +// UNSUPPORTED: android + +#include +#include +#include +#include +#include +#include + +int main() { + int fd_0 = socket(AF_INET, SOCK_DGRAM, 0); + int fd_1 = socket(AF_INET, SOCK_DGRAM, 0); + struct sockaddr_in sin; + socklen_t len = sizeof(sin); + char *buf = (char *)malloc(1); + + sin.sin_family = AF_INET; + // Choose a random port to bind. + sin.sin_port = 0; + sin.sin_addr.s_addr = INADDR_ANY; + + assert(bind(fd_1, (struct sockaddr *)&sin, sizeof(sin)) == 0); + // Get the address and port binded. + assert(getsockname(fd_1, (struct sockaddr *)&sin, &len) == 0); + assert(sendto(fd_0, "hello", strlen("hello"), MSG_DONTWAIT, + (struct sockaddr *)&sin, sizeof(sin)) != -1); + assert(recv(fd_1, buf, 1, MSG_TRUNC) != -1); + free(buf); + + return 0; +} +