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Date: Fri, 07 Aug 2020 13:51:12 -0400 From: "Alex Xu (Hello71)" <alex_y_xu@...oo.ca> To: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>, Linus Torvalds <torvalds@...ux-foundation.org> Cc: Christian Brauner <christian.brauner@...ntu.com>, Aleksa Sarai <cyphar@...har.com>, Christoph Hellwig <hch@....de>, Kees Cook <keescook@...omium.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Matt Denton <mpdenton@...gle.com>, Chris Palmer <palmer@...gle.com>, Robert Sesek <rsesek@...gle.com>, Sargun Dhillon <sargun@...gun.me>, Shuah Khan <shuah@...nel.org>, Tycho Andersen <tycho@...ho.ws>, Will Drewry <wad@...omium.org>, Will Deacon <will@...nel.org>, Yonghong Song <yhs@...com> Subject: Re: wine fails to start with seccomp updates for v5.9-rc1 Excerpts from Thadeu Lima de Souza Cascardo's message of August 7, 2020 1:36 pm: > On Fri, Aug 07, 2020 at 08:48:46AM -0700, Linus Torvalds wrote: >> On Fri, Aug 7, 2020 at 8:19 AM Alex Xu (Hello71) <alex_y_xu@...oo.ca> wrote: >> > >> > On Linus' master, wine fails to start with the following error: >> > >> > wine client error:0: write: Bad file descriptor >> > >> > This issue is not present on 5.8. It appears to be caused by failure to >> > write to a pipe FD received via SCM_RIGHTS. Therefore, I tried reverting >> > 9ecc6ea491f0, which resolved the issue. >> >> Would you mind trying to bisect exactly where it happens? >> > > This report [1] seemed related and pointed out at c0029de50982 ("net/scm: > Regularize compat handling of scm_detach_fds()"). The use of CMSG_USER_DATA > instead of CMSG_COMPAT_DATA seems fishy. > > Alex, can you try applying the patch below? > > Cascardo. > > [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2020-August/216156.html > >> I don't think any of the commits in that pull are supposed to change >> semantics, and while reverting the whole merge shows that yes, that's >> what brought in the problems, it would be good to pinpoint just which >> change breaks so that we can fix just that thing. >> >> Kees, ideas? >> >> Linus > > --- > diff --git a/net/compat.c b/net/compat.c > index 703acb51c698..95ce707a30a3 100644 > --- a/net/compat.c > +++ b/net/compat.c > @@ -294,7 +294,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm) > (struct compat_cmsghdr __user *)msg->msg_control; > unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0; > int fdmax = min_t(int, scm_max_fds_compat(msg), scm->fp->count); > - int __user *cmsg_data = CMSG_USER_DATA(cm); > + int __user *cmsg_data = CMSG_COMPAT_DATA(cm); > int err = 0, i; > > for (i = 0; i < fdmax; i++) { > Yes, this seems to work. Tested-by: Alex Xu (Hello71) <alex_y_xu@...oo.ca> Thanks!
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