| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20250515152557.a4q2cqab4uvhnpia@desk>
Date: Thu, 15 May 2025 08:25:57 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Guenter Roeck <linux@...ck-us.net>,
Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>,
stable@...r.kernel.org, patches@...ts.linux.dev,
linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, shuah@...nel.org, patches@...nelci.org,
lkft-triage@...ts.linaro.org, pavel@...x.de, jonathanh@...dia.com,
f.fainelli@...il.com, sudipm.mukherjee@...il.com,
srw@...dewatkins.net, rwarsow@....de, conor@...nel.org,
hargar@...rosoft.com, broonie@...nel.org,
Darren Kenny <darren.kenny@...cle.com>
Subject: Re: [PATCH 6.6 000/113] 6.6.91-rc2 review
On Thu, May 15, 2025 at 07:35:26AM +0200, Greg Kroah-Hartman wrote:
> On Wed, May 14, 2025 at 01:49:06PM -0700, Guenter Roeck wrote:
> > On 5/14/25 13:33, Harshit Mogalapalli wrote:
> > > Hi Greg,
> > >
> > > On 15/05/25 01:35, Greg Kroah-Hartman wrote:
> > > > On Thu, May 15, 2025 at 12:29:40AM +0530, Harshit Mogalapalli wrote:
> > > > > Hi Greg,
> > > > > On 14/05/25 18:34, Greg Kroah-Hartman wrote:
> > > > > > This is the start of the stable review cycle for the 6.6.91 release.
> > > > > > There are 113 patches in this series, all will be posted as a response
> > > > > > to this one. If anyone has any issues with these being applied, please
> > > > > > let me know.
> > > > > >
> > > > > > Responses should be made by Fri, 16 May 2025 12:55:38 +0000.
> > > > > > Anything received after that time might be too late.
> > > > >
> > > > > ld: vmlinux.o: in function `patch_retpoline':
> > > > > alternative.c:(.text+0x3b6f1): undefined reference to `module_alloc'
> > > > > make[2]: *** [scripts/Makefile.vmlinux:37: vmlinux] Error 1
> > > > >
> > > > > We see this build error in 6.6.91-rc2 tag.
> > > >
> > > > What is odd about your .config? Have a link to it? I can't duplicate
> > > > it here on my builds.
> > > >
> > >
> > > So this is a config where CONFIG_MODULES is unset(!=y) -- with that we could reproduce it on defconfig + disabling CONFIG_MODULES as well.
> > >
> >
> > Key is the combination of CONFIG_MODULES=n with CONFIG_MITIGATION_ITS=y.
>
> Ah, this is due to the change in its_alloc() for 6.6.y and 6.1.y by the
> call to module_alloc() instead of execmem_alloc() in the backport of
> 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches").
Sorry for the trouble. I wish I had a test to catch problems like this. The
standard config targets defconfig, allyesconfig, allnoconfig, etc. do not
expose such issues. The only thing that comes close is randconfig.
CONFIG_MODULES=n is not a common setting, I wonder how people find such
issues? (trying to figure out how to prevent such issues in future).
> Pawan, any hints on what should be done here instead?
Since dynamic thunks are not possible without CONFIG_MODULES, one option is
to adjust the already in 6.6.91-rc2 patch 9f35e331144a (x86/its: Fix build
errors when CONFIG_MODULES=n) to also bring the ITS thunk allocation under
CONFIG_MODULES.
I am not seeing any issue with below build and boot test:
#!/bin/bash -ex
./scripts/config --disable CONFIG_MODULES
./scripts/config --disable CONFIG_MITIGATION_ITS
# https://github.com/arighi/virtme-ng
vng -b
vng -- lscpu
# main test
./scripts/config --disable CONFIG_MODULES
./scripts/config --enable CONFIG_MITIGATION_ITS
vng -b
vng -- lscpu
./scripts/config --enable CONFIG_MODULES
./scripts/config --disable CONFIG_MITIGATION_ITS
vng -b
vng -- lscpu
./scripts/config --enable CONFIG_MODULES
./scripts/config --enable CONFIG_MITIGATION_ITS
vng -b
vng -- lscpu
echo "PASS"
Similar change is required for 6.1 and 5.15 as well. 6.12 is fine because
it uses execmem_alloc().
--- 8< ---
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Subject: [PATCH 6.6] x86/its: Fix build errors when CONFIG_MODULES=n
From: Eric Biggers <ebiggers@...gle.com>
commit 9f35e33144ae5377d6a8de86dd3bd4d995c6ac65 upstream.
Fix several build errors when CONFIG_MODULES=n, including the following:
../arch/x86/kernel/alternative.c:195:25: error: incomplete definition of type 'struct module'
195 | for (int i = 0; i < mod->its_num_pages; i++) {
[ pawan: backport: Bring ITS dynamic thunk code under CONFIG_MODULES ]
Fixes: 872df34d7c51 ("x86/its: Use dynamic thunks for indirect branches")
Cc: stable@...r.kernel.org
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Acked-by: Dave Hansen <dave.hansen@...el.com>
Tested-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/kernel/alternative.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 6085919d3b3e..c6d9a3882ec8 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -129,6 +129,7 @@ const unsigned char * const x86_nops[ASM_NOP_MAX+1] =
#ifdef CONFIG_MITIGATION_ITS
+#ifdef CONFIG_MODULES
static struct module *its_mod;
static void *its_page;
static unsigned int its_offset;
@@ -244,7 +245,16 @@ static void *its_allocate_thunk(int reg)
return thunk;
}
-#endif
+#else /* CONFIG_MODULES */
+
+static void *its_allocate_thunk(int reg)
+{
+ return NULL;
+}
+
+#endif /* CONFIG_MODULES */
+
+#endif /* CONFIG_MITIGATION_ITS */
/*
* Fill the buffer with a single effective instruction of size @len.
--
2.34.1
Powered by blists - more mailing lists