On Thu, Jun 01, 2023 at 09:26:30AM -0400, Luiz Capitulino wrote:
On 2023-06-01 09:20, Greg KH wrote:
On Thu, Jun 01, 2023 at 09:13:21AM -0400, Luiz Capitulino wrote:
On 2023-06-01 02:06, Greg KH wrote:
On Wed, May 31, 2023 at 10:12:40PM -0400, Luiz Capitulino wrote:
Hi Paul,
A number of stable kernels recently backported this upstream commit:
""" commit 4ce1f694eb5d8ca607fed8542d32a33b4f1217a5 Author: Paul Moore paul@paul-moore.com Date: Wed Apr 12 13:29:11 2023 -0400
selinux: ensure av_permissions.h is built when needed"""
We're seeing a build issue with this commit where the "crash" tool will fail to start, it complains that the vmlinux image and /proc/version don't match.
A minimum reproducer would be having "make" version before 4.3 and building the kernel with:
$ make bzImages $ make modules
Then compare the version strings in the bzImage and vmlinux images, we can use "strings" for this. For example, in the 5.10.181 kernel I get:
$ strings vmlinux | egrep '^Linux version' Linux version 5.10.181 (ec2-user@ip-172-31-79-134.ec2.internal) (gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-15), GNU ld version 2.29.1-31.amzn2) #2 SMP Thu Jun 1 01:26:38 UTC 2023
$ strings ./arch/x86_64/boot/bzImage | egrep 'ld version' 5.10.181 (ec2-user@ip-172-31-79-134.ec2.internal) (gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-15), GNU ld version 2.29.1-31.amzn2) #1 SMP Thu Jun 1 01:23:59 UTC 2023
The version string in the bzImage doesn't have the "Linux version" part, but I think this is added by the kernel when printing. If you compare the strings, you'll see that they have a different build date and the "#1" and "#2" are different.
This only happens with commit 4ce1f694eb5 applied and older "make", in my case I have "make" version 3.82.
If I revert 4ce1f694eb5 or use "make" version 4.3 I get identical strings (except for the "Linux version" part):
$ strings vmlinux | egrep '^Linux version' Linux version 5.10.181+ (ec2-user@ip-172-31-79-134.ec2.internal) (gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-15), GNU ld version 2.29.1-31.amzn2) #1 SMP Thu Jun 1 01:29:11 UTC 2023
$ strings ./arch/x86_64/boot/bzImage | egrep 'ld version' 5.10.181+ (ec2-user@ip-172-31-79-134.ec2.internal) (gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-15), GNU ld version 2.29.1-31.amzn2) #1 SMP Thu Jun 1 01:29:11 UTC 2023
Maybe the grouped target usage in 4ce1f694eb5 with older "make" is causing a rebuild of the vmlinux image in "make modules"? If yes, is this expected?
I'm afraid this issue could be high impact for distros with older user-space.
Is this issue also in 6.4-rc1 where this change came from?
Yes. I'm reporting this here because I'm more concerned with -stable kernels since they're more likely to be running on older user-space.
Yeah, we are bug-compatible! :)
When this gets fixed in Linus's tree, I'll be glad to backport the changes to the other kernels. Please work with the developers to get that fixed there.
OK, I'll report it there, but shouldn't we avoid regressing -stable kernels?
We should avoid regressing Linus's kernel tree just as much. It's always been this way, I don't want to revert patches unless they are really bad if the fix is not in Linus's tree already. Gives people "encouragement" to resolve the issue quicker.
thanks,
greg k-h