On 3/25/20 4:10 PM, Eric W. Biederman wrote:

Bernd Edlinger bernd.edlinger@hotmail.de writes:

...

This is an infrastructure change that makes way for fixing this issue. Each patch was already posted previously so this is just a cleanup of the original mailing list thread(s) which got out of control by now.

Everything started here: https://lore.kernel.org/lkml/AM6PR03MB5170B06F3A2B75EFB98D071AE4E60@AM6PR03M...

I added reviewed-by tags from the mailing list threads, except when withdrawn.

It took a lot longer than expected to collect everything from the mailinglist threads, since several commit messages have been infected with typos, and they got fixed without a new patch version.

• Correct the point of no return.
• Add two new mutexes to replace cred_guard_mutex.
• Fix each use of cred_guard_mutex.
• Update documentation.
• Add a test case.

Bernd Edlinger (11): exec: Fix a deadlock in strace selftests/ptrace: add test cases for dead-locks mm: docs: Fix a comment in process_vm_rw_core kernel: doc: remove outdated comment cred.c kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve proc: Use new infrastructure to fix deadlocks in execve proc: io_accounting: Use new infrastructure to fix deadlocks in execve perf: Use new infrastructure to fix deadlocks in execve pidfd: Use new infrastructure to fix deadlocks in execve exec: Fix dead-lock in de_thread with ptrace_attach doc: Update documentation of ->exec_*_mutex

Eric W. Biederman (5): exec: Only compute current once in flush_old_exec exec: Factor unshare_sighand out of de_thread and call it separately exec: Move cleanup of posix timers on exec out of de_thread exec: Move exec_mmap right after de_thread in flush_old_exec exec: Add exec_update_mutex to replace cred_guard_mutex

Documentation/security/credentials.rst | 29 +++++-- fs/exec.c | 122 ++++++++++++++++++++++-------- fs/proc/base.c | 23 +++--- include/linux/binfmts.h | 8 +- include/linux/sched/signal.h | 17 ++++- init/init_task.c | 3 +- kernel/cred.c | 4 +- kernel/events/core.c | 12 +-- kernel/fork.c | 7 +- kernel/kcmp.c | 8 +- kernel/pid.c | 4 +- kernel/ptrace.c | 20 ++++- kernel/seccomp.c | 15 ++-- mm/process_vm_access.c | 2 +- tools/testing/selftests/ptrace/Makefile | 4 +- tools/testing/selftests/ptrace/vmaccess.c | 86 +++++++++++++++++++++ 16 files changed, 278 insertions(+), 86 deletions(-) create mode 100644 tools/testing/selftests/ptrace/vmaccess.c

Two small nits.

• You reposted my patches with adding your signed-off-by
• You reposted my patches and did not include a "From:" in the body so "git am" listed you as the author.

I have fixed those up and will be merging this code to linux-next, unless you object.

Thanks, I have not expected that a From: which names a different domain than hotmail.de would be forwarded by the SMTP servers I have to use. Actually I was not even aware of the problem at all.

The Patch "exec: Add exec_update_mutex to replace cred_guard_mutex" was initially reviewed-by: bernd.edlinger@hotmail.de but it turned out to be faulty, so I update your patch faithfully, and did a small change to fix the patch, therefore it is actually 99% your and 1% my patch, therefore I figured I should be in a signed-off-by: together with you. BTW: I saw a Reviewed-by: Kirill Tkhai ktkhai@virtuozzo.com on the mailing list, you should add that as well.

Thanks Bernd.

On Sat, Mar 28, 2020 at 11:32:35PM +0100, Bernd Edlinger wrote:

Oh, do I understand you right, that I can add a From: in the *body* of the mail, and then the From: in the MIME header part which I cannot change is ignored, so I can make you the author?

Correct. (If you use "git send-email" it'll do this automatically.)

e.g., trimmed from my workflow:

git format-patch -n --to "$to" --cover-letter -o outgoing/ \ --subject-prefix "PATCH v$version" "$SHA" edit outgoing/0000-* git send-email --transfer-encoding=8bit --8bit-encoding=UTF-8 \ --from="$ME" --to="$to" --cc="$ME" --cc="...more..." outgoing/*

On Mon, Mar 30, 2020 at 10:12:02PM +0200, Bernd Edlinger wrote:

On 3/29/20 5:44 AM, Kees Cook wrote:

...

On Sat, Mar 28, 2020 at 11:32:35PM +0100, Bernd Edlinger wrote:

...

Oh, do I understand you right, that I can add a From: in the *body* of the mail, and then the From: in the MIME header part which I cannot change is ignored, so I can make you the author?

Correct. (If you use "git send-email" it'll do this automatically.)

e.g., trimmed from my workflow:

git format-patch -n --to "$to" --cover-letter -o outgoing/ \ --subject-prefix "PATCH v$version" "$SHA" edit outgoing/0000-* git send-email --transfer-encoding=8bit --8bit-encoding=UTF-8 \ --from="$ME" --to="$to" --cc="$ME" --cc="...more..." outgoing/*

Okay, thanks, I see that is very helpful information for me, and in this case I had also fixed a small bug in one of Eric's patches, which was initially overlooked (aquiring mutexes in wrong order, releasing an unlocked mutex in some error paths). I am completely unexperienced, and something that complex was not expected to happen :-) so this is just to make sure I can handle it correctly if something like this happens again.

In the case of PATCH v6 05/16 I removed the Reviewd-by: Bernd Edlinger since it is now somehow two authors and reviewing own code is obviously not ok, instead I added a Signed-off-by: Bernd Edlinger (and posted the whole series on Eric's behalf (after asking Eric's permissing per off-list e-mail, which probably ended in his spam folder)

Is this having two Signed-off-by: for mutliple authors the correct way to handle a shared authorship?

If the patch comes through you, then Reviewed-by: is inappropriate. Instead, you should use Signed-off-by: in the second sense of Documentation/process/submitting-patches.rst

This also documents how to handle "minor changes" that you make.

On 4/2/20 9:40 AM, Kees Cook wrote:

On Mon, Mar 30, 2020 at 01:14:59PM -0700, Matthew Wilcox wrote:

...

On Mon, Mar 30, 2020 at 10:12:02PM +0200, Bernd Edlinger wrote:

...

On 3/29/20 5:44 AM, Kees Cook wrote:

...

On Sat, Mar 28, 2020 at 11:32:35PM +0100, Bernd Edlinger wrote:

...

Oh, do I understand you right, that I can add a From: in the *body* of the mail, and then the From: in the MIME header part which I cannot change is ignored, so I can make you the author?

Correct. (If you use "git send-email" it'll do this automatically.)

e.g., trimmed from my workflow:

git format-patch -n --to "$to" --cover-letter -o outgoing/ \ --subject-prefix "PATCH v$version" "$SHA" edit outgoing/0000-* git send-email --transfer-encoding=8bit --8bit-encoding=UTF-8 \ --from="$ME" --to="$to" --cc="$ME" --cc="...more..." outgoing/*

Okay, thanks, I see that is very helpful information for me, and in this case I had also fixed a small bug in one of Eric's patches, which was initially overlooked (aquiring mutexes in wrong order, releasing an unlocked mutex in some error paths). I am completely unexperienced, and something that complex was not expected to happen :-) so this is just to make sure I can handle it correctly if something like this happens again.

In the case of PATCH v6 05/16 I removed the Reviewd-by: Bernd Edlinger since it is now somehow two authors and reviewing own code is obviously not ok, instead I added a Signed-off-by: Bernd Edlinger (and posted the whole series on Eric's behalf (after asking Eric's permissing per off-list e-mail, which probably ended in his spam folder)

Is this having two Signed-off-by: for mutliple authors the correct way to handle a shared authorship?

If the patch comes through you, then Reviewed-by: is inappropriate. Instead, you should use Signed-off-by: in the second sense of Documentation/process/submitting-patches.rst

This also documents how to handle "minor changes" that you make.

And in the true case of multiple authors, have both SoBs, but also add a Co-developed-by: for the non-"git author" author. Specific details: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-...

Thanks a lot, much appreciated information indeed.

I personally like to play together :-)

Bernd.