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Re: [Qemu-devel] [PATCH] msmouse: Fix segfault caused by free the chr be
From: |
Marc-André Lureau |
Subject: |
Re: [Qemu-devel] [PATCH] msmouse: Fix segfault caused by free the chr before chardev cleanup. |
Date: |
Thu, 15 Sep 2016 10:59:25 -0400 (EDT) |
Hi
----- Original Message -----
> Segfault happens when leaving qemu with msmouse backend:
>
> #0 0x00007fa8526ac975 in raise () at /lib64/libc.so.6
> #1 0x00007fa8526add8a in abort () at /lib64/libc.so.6
> #2 0x0000558be78846ab in error_exit (err=16, msg=0x558be799da10 ...
> #3 0x0000558be7884717 in qemu_mutex_destroy (mutex=0x558be93be750) at ...
> #4 0x0000558be7549951 in qemu_chr_free_common (chr=0x558be93be750) at ...
> #5 0x0000558be754999c in qemu_chr_free (chr=0x558be93be750) at ...
> #6 0x0000558be7549a20 in qemu_chr_delete (chr=0x558be93be750) at ...
> #7 0x0000558be754a8ef in qemu_chr_cleanup () at qemu-char.c:4643
> #8 0x0000558be755843e in main (argc=5, argv=0x7ffe925d7118, ...
>
> The chr was freed by msmouse close callback before chardev cleanup,
> Then qemu_mutex_destroy triggered raise().
>
> Because freeing chr is handled by qemu_chr_free_common, Remove the free from
> msmouse_chr_close to avoid double free.
>
> Signed-off-by: Lin Ma <address@hidden>
Reviewed-by: Marc-André Lureau <address@hidden>
> ---
> backends/msmouse.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/backends/msmouse.c b/backends/msmouse.c
> index aeb9055..7690c42 100644
> --- a/backends/msmouse.c
> +++ b/backends/msmouse.c
> @@ -139,7 +139,6 @@ static void msmouse_chr_close (struct CharDriverState
> *chr)
>
> qemu_input_handler_unregister(mouse->hs);
> g_free(mouse);
> - g_free(chr);
> }
Ooch, chr_close is not supposed to free chr! There might be other cases where
memory corruption could occur.
>
> static QemuInputHandler msmouse_handler = {
> --
> 2.9.2
>
>