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[Qemu-devel] [PULL v2 26/38] linux-user: Use safe_syscall for execve sys
From: |
riku . voipio |
Subject: |
[Qemu-devel] [PULL v2 26/38] linux-user: Use safe_syscall for execve syscall |
Date: |
Fri, 27 May 2016 16:00:17 +0300 |
From: Timothy E Baldwin <address@hidden>
Wrap execve() in the safe-syscall handling. Although execve() is not
an interruptible syscall, it is a special case: if we allow a signal
to happen before we make the host$ syscall then we will 'lose' it,
because at the point of execve the process leaves QEMU's control. So
we use the safe syscall wrapper to ensure that we either take the
signal as a guest signal, or else it does not happen before the
execve completes and makes it the other program's problem.
The practical upshot is that without this SIGTERM could fail to
terminate the process.
Signed-off-by: Timothy Edward Baldwin <address@hidden>
Message-id: address@hidden
[PMM: expanded commit message to explain in more detail why this is
needed, and add comment about it too]
Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Peter Maydell <address@hidden>
Signed-off-by: Riku Voipio <address@hidden>
---
linux-user/syscall.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index d9f4695..dea827f 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -703,6 +703,7 @@ safe_syscall4(pid_t, wait4, pid_t, pid, int *, status, int,
options, \
struct rusage *, rusage)
safe_syscall5(int, waitid, idtype_t, idtype, id_t, id, siginfo_t *, infop, \
int, options, struct rusage *, rusage)
+safe_syscall3(int, execve, const char *, filename, char **, argv, char **,
envp)
static inline int host_to_target_sock_type(int host_type)
{
@@ -6179,7 +6180,17 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
arg1,
if (!(p = lock_user_string(arg1)))
goto execve_efault;
- ret = get_errno(execve(p, argp, envp));
+ /* Although execve() is not an interruptible syscall it is
+ * a special case where we must use the safe_syscall wrapper:
+ * if we allow a signal to happen before we make the host
+ * syscall then we will 'lose' it, because at the point of
+ * execve the process leaves QEMU's control. So we use the
+ * safe syscall wrapper to ensure that we either take the
+ * signal as a guest signal, or else it does not happen
+ * before the execve completes and makes it the other
+ * program's problem.
+ */
+ ret = get_errno(safe_execve(p, argp, envp));
unlock_user(p, arg1, 0);
goto execve_end;
--
2.1.4
- [Qemu-devel] [PULL v2 17/38] linux-user: Support for restarting system calls for CRIS targets, (continued)
- [Qemu-devel] [PULL v2 17/38] linux-user: Support for restarting system calls for CRIS targets, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 18/38] linux-user: Support for restarting system calls for tilegx targets, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 23/38] linux-user: Use safe_syscall for read and write system calls, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 20/38] linux-user: Support for restarting system calls for Microblaze targets, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 21/38] linux-user: Add debug code to exercise restarting system calls, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 19/38] linux-user: Set r14 on exit from microblaze syscall, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 22/38] linux-user: Provide safe_syscall for fixing races between signals and syscalls, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 24/38] linux-user: Use safe_syscall for open and openat system calls, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 25/38] linux-user: Use safe_syscall for wait system calls, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 29/38] linux-user: Handle negative values in timespec conversion, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 26/38] linux-user: Use safe_syscall for execve syscall,
riku . voipio <=
- [Qemu-devel] [PULL v2 27/38] linux-user: Use safe_syscall for pselect, select syscalls, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 28/38] linux-user: Use safe_syscall for futex syscall, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 31/38] linux-user: Use g_try_malloc() in do_msgrcv(), riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 33/38] linux-user: Use direct syscalls for setuid(), etc, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 34/38] linux-user: arm: Remove ARM_cpsr and similar #defines, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 30/38] linux-user: Handle msgrcv error case correctly, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 32/38] linux-user: x86_64: Don't use 16-bit UIDs, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 35/38] linux-user/signal.c: Generate opcode data for restorer in setup_rt_frame, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 37/38] linux-user/signal.c: Use s390 target space address instead of host space, riku . voipio, 2016/05/27
- [Qemu-devel] [PULL v2 36/38] linux-user/signal.c: Use target address instead of host address for microblaze restorer, riku . voipio, 2016/05/27