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[Qemu-devel] [PATCH resent] linux-user: in poll(), if nfds is 0, pfd can
From: |
Laurent Vivier |
Subject: |
[Qemu-devel] [PATCH resent] linux-user: in poll(), if nfds is 0, pfd can be NULL |
Date: |
Tue, 6 Oct 2015 01:20:48 +0200 |
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 <address@hidden>
---
This patch has already been sent in April, this version is just rebased on
master.
https://patchwork.ozlabs.org/patch/460950/
linux-user/syscall.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 98b5766..9cdb2a2 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7893,14 +7893,20 @@ 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
--
2.4.3
- [Qemu-devel] [PATCH resent] linux-user: in poll(), if nfds is 0, pfd can be NULL,
Laurent Vivier <=