[PATCH] gdbstub: Fix double close() of the follow-fork-mode socket

[PATCH] gdbstub: Fix double close() of the follow-fork-mode socket

[Ilya Leoshkevich]

When the terminal GDB_FORK_ENABLED state is reached, the coordination
socket is not needed anymore and is therefore closed. However, if there
is a communication error between QEMU gdbstub and GDB, the generic
error handling code attempts to close it again.

Fix by closing it later - before returning - instead.

Fixes: Coverity CID 1539966
Fixes: d547e711a8a5 ("gdbstub: Implement follow-fork-mode child")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 gdbstub/user.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/gdbstub/user.c b/gdbstub/user.c
index 7f9f19a1249..08aed022e26 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -502,6 +502,7 @@ void gdbserver_fork_end(CPUState *cpu, pid_t pid)
         switch (gdbserver_user_state.fork_state) {
         case GDB_FORK_ENABLED:
             if (gdbserver_user_state.running_state) {
+                close(fd);
                 return;
             }
             QEMU_FALLTHROUGH;
@@ -527,7 +528,6 @@ void gdbserver_fork_end(CPUState *cpu, pid_t pid)
                 gdbserver_user_state.fork_state = GDB_FORK_ACTIVE;
                 break;
             case GDB_FORK_ENABLE:
-                close(fd);
                 gdbserver_user_state.fork_state = GDB_FORK_ENABLED;
                 break;
             case GDB_FORK_DISABLE:
@@ -542,7 +542,6 @@ void gdbserver_fork_end(CPUState *cpu, pid_t pid)
             if (write(fd, &b, 1) != 1) {
                 goto fail;
             }
-            close(fd);
             gdbserver_user_state.fork_state = GDB_FORK_ENABLED;
             break;
         case GDB_FORK_DISABLING:
-- 
2.44.0

Re: [PATCH] gdbstub: Fix double close() of the follow-fork-mode socket

[Alex Bennée]

Ilya Leoshkevich <iii@linux.ibm.com> writes:

> When the terminal GDB_FORK_ENABLED state is reached, the coordination
> socket is not needed anymore and is therefore closed. However, if there
> is a communication error between QEMU gdbstub and GDB, the generic
> error handling code attempts to close it again.
>
> Fix by closing it later - before returning - instead.
>
> Fixes: Coverity CID 1539966
> Fixes: d547e711a8a5 ("gdbstub: Implement follow-fork-mode child")
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

Queued to gdbstub/next, thanks.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro