@@ -89,6 +89,17 @@ static int global_state_post_load(void *opaque, int version_id)
s->received = true;
trace_migrate_global_state_post_load(runstate);
+ if (strnlen((char *)s->runstate,
+ sizeof(s->runstate)) == sizeof(s->runstate)) {
+ /*
+ * This condition should never happen during migration, because
+ * all runstate names are shorter than 100 bytes (the size of
+ * s->runstate). However, a malicious stream could overflow
+ * the qapi_enum_parse() call, so we force the last character
+ * to a NUL byte.
+ */
+ s->runstate[sizeof(s->runstate) - 1] = '\0';
+ }
r = qapi_enum_parse(&RunState_lookup, runstate, -1, &local_err);
if (r == -1) {
@@ -107,7 +118,8 @@ static int global_state_pre_save(void *opaque)
GlobalState *s = opaque;
trace_migrate_global_state_pre_save((char *)s->runstate);
- s->size = strlen((char *)s->runstate) + 1;
+ s->size = strnlen((char *)s->runstate, sizeof(s->runstate)) + 1;
+ assert(s->size <= sizeof(s->runstate));
return 0;
}
GCC 8 introduced the -Wstringop-overflow, which detect buffer overflow by string-modifying functions declared in <string.h>, such strncpy(), used in global_state_store_running(). GCC indeed found an incorrect use of strlen(), because this array is loaded by VMSTATE_BUFFER(runstate, GlobalState) then parsed using qapi_enum_parse which does not get the buffer length. Use strnlen() which returns sizeof(s->runstate) if the array is not NUL-terminated, assert the size is within range, and enforce the array to be NUL-terminated to avoid an overflow in qapi_enum_parse(). This fixes: CC migration/global_state.o qemu/migration/global_state.c: In function 'global_state_pre_save': qemu/migration/global_state.c:109:15: error: 'strlen' argument 1 declared attribute 'nonstring' [-Werror=stringop-overflow=] s->size = strlen((char *)s->runstate) + 1; ^~~~~~~~~~~~~~~~~~~~~~~~~~~ qemu/migration/global_state.c:24:13: note: argument 'runstate' declared here uint8_t runstate[100] QEMU_NONSTRING; ^~~~~~~~ cc1: all warnings being treated as errors make: *** [qemu/rules.mak:69: migration/global_state.o] Error 1 Suggested-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> --- v5: Use Linux-kernel-style multiline comments --- migration/global_state.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)