From: Laurent Vivier Date: Mon, 5 Oct 2015 23:20:48 +0000 (+0200) Subject: linux-user: in poll(), if nfds is 0, pfd can be NULL X-Git-Tag: v2.6.0-rc0~232^2~14 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3e24bb3f1277ee25743f0a3274306080df80da2c;p=thirdparty%2Fqemu.git 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 #include 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 Signed-off-by: Riku Voipio --- diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 8fa8e0ce14a..c2169664d5d 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -8046,14 +8046,20 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, 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