linux-user: in poll(), if nfds is 0, pfd can be NULL
This problem appears with yum in Fedora 20 / PPC64 container.
test case:
#include <stdio.h>
#include <poll.h>
int main(void)
{
int ret;
ret = poll(NULL, 0, 1000);
printf("%d\n", ret);
}
target test environment: Fedora 20 / PPC64
host test environment: Ubuntu 14.0.2 / x86_64
original test result: -1
13451 poll(0,0,1000,274886297496,268566664,268566648) = -1 errno=14 (Bad address)
patched test result: 0
13536 poll(0,0,1000,274886297496,268566664,268566648) = 0
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 8fa8e0c..c216966 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8046,14 +8046,20 @@
struct pollfd *pfd;
unsigned int i;
- target_pfd = lock_user(VERIFY_WRITE, arg1, sizeof(struct target_pollfd) * nfds, 1);
- if (!target_pfd)
- goto efault;
+ pfd = NULL;
+ target_pfd = NULL;
+ if (nfds) {
+ target_pfd = lock_user(VERIFY_WRITE, arg1,
+ sizeof(struct target_pollfd) * nfds, 1);
+ if (!target_pfd) {
+ goto efault;
+ }
- pfd = alloca(sizeof(struct pollfd) * nfds);
- for(i = 0; i < nfds; i++) {
- pfd[i].fd = tswap32(target_pfd[i].fd);
- pfd[i].events = tswap16(target_pfd[i].events);
+ pfd = alloca(sizeof(struct pollfd) * nfds);
+ for (i = 0; i < nfds; i++) {
+ pfd[i].fd = tswap32(target_pfd[i].fd);
+ pfd[i].events = tswap16(target_pfd[i].events);
+ }
}
# ifdef TARGET_NR_ppoll
