kernel 5.16.12 & 5.15.25 & 5.10.103 issue with /aufs/fsctx.c #9

peabee · 2022-03-06T10:56:00Z

An issue has arisen with kernel 5.16.12 patched with aufs and used in Puppy Linux.
The issue was not present in kernel 5.16.7
A system crash occurs when initial shutdown occurs and a new persistent user save area should be created
The crash message mentions au_fsctx_parse_monolithic
which is a function in aufs/fsctx.c

peabee · 2022-03-06T14:52:00Z

Kernel 5.15.25 also crashes on shutdown.

sfjro · 2022-03-06T22:32:38Z

Hello PB, I've got an empty message from you via github. But it's OK since I've checked #9 and saw the problem. I cannot reproduce the problem but I can guess the cause. Here is a patch for you. Please test. J. R. Okajima

sfjro · 2022-03-06T22:57:21Z

I've got an empty message from you via github. But it's OK since I've checked #9 and saw the problem. I cannot reproduce the problem but I can guess the cause. Here is a patch for you. Please test.

And next time when you report a problem, please describe the first line of the kernel message, such as "NULL pointer is accessed". J. R. Okajima

sfjro · 2022-03-06T23:00:19Z

I've got an empty message from you via github. But it's OK since I've checked #9 and saw the problem. I cannot reproduce the problem but I can guess the cause. Here is a patch for you. Please test.

Ah, github ate the attached patch in my previous messages. Here I include it as a plain text. Please test. J. R. Okajima diff --git a/fs/aufs/fsctx.c b/fs/aufs/fsctx.c index aa9b444438c20..739531e2d2908 100644 --- a/fs/aufs/fsctx.c +++ b/fs/aufs/fsctx.c @@ -1091,7 +1091,7 @@ static int au_fsctx_parse_monolithic(struct fs_context *fc, void *data) str = data; AuDbg("str %s\n", str); - while (1) { + while (str) { u = is_colonopt(str); if (u) str[u] = '=';

peabee · 2022-03-07T10:03:45Z

My apologies for the blank message - I accidentally hit the button before completing the entry - sorry.
I believe that I have done a build of 5.16.12 with the patch you have suggested, but sadly the crash still occurs.
The crash report says:

BUG: kernel NULL pointer dereference
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page

sfjro · 2022-03-07T11:13:16Z

PB:

I believe that I have done a build of 5.16.12 with the patch you have suggested, but sadly the crash still occurs. The crash report says: > BUG: kernel NULL pointer dereference

Hmm, am I going totally wrong direction? (I'm talking to myself) To confirm this, would you try this patch and test again? J. R. Okajima diff --git a/fs/aufs/fsctx.c b/fs/aufs/fsctx.c index e5622fc17..23c3fa19a 100644 --- a/fs/aufs/fsctx.c +++ b/fs/aufs/fsctx.c @@ -1100,8 +1100,12 @@ static int au_fsctx_parse_monolithic(struct fs_context *fc, void *data) int err; unsigned int u; char *str; - struct au_fsctx_opts *a = fc->fs_private; + struct au_fsctx_opts *a; + err = 0; + if (!fc || !data) + goto out; + a = fc->fs_private; str = data; AuDbg("str %s\n", str); while (str) { @@ -1120,6 +1124,7 @@ static int au_fsctx_parse_monolithic(struct fs_context *fc, void *data) AuTraceErr(err); au_fsctx_dump(&a->opts); +out: return err; }

peabee · 2022-03-07T13:29:09Z

Yes - thank you - with the 2nd patch the crashes stop......... kernel 5.16.12 :-))
I can't apply the patch to the 5.15.25 kernel due to the way it is built....
I also didn't check whether 5.10 is also affected........ but can do so if needed

static int au_fsctx_parse_monolithic(struct fs_context *fc, void *data)
{
	int err;
	unsigned int u;
	char *str;
	struct au_fsctx_opts *a;

	err = 0;
	if (!fc || !data)
	goto out;
	a = fc->fs_private;
	str = data;
	AuDbg("str %s\n", str);
	while (str) {
		u = is_colonopt(str);
		if (u)
			str[u] = '=';
		str = strchr(str, ',');
		if (!str)
			break;
		str++;
	}
	str = data;
	AuDbg("str %s\n", str);

	err = generic_parse_monolithic(fc, str);
	AuTraceErr(err);
	au_fsctx_dump(&a->opts);

out:
	return err;
}

peabee · 2022-03-07T13:59:10Z

Have now checked - 5.10.103 also needs the patch

sfjro · 2022-03-07T23:17:54Z

PB:

Yes - thank you - with the 2nd patch the crashes stop......... kernel 5.16.12 :-))

Thanx for testing. But yet I am not fully convinced. Did you enable CONFIG_AUFS_DEBUG in the kernel configuration? And set the module parameter "debug=1" or ran "AuDebug 1" (which is a shell function defined in /etc/default/aufs)? Otherwise the problem should not happen I am afraid. The file fs/aufs/fsctx.c was introduced aufs5.10 and after, and every version potentially has this bug. The reproducible conditions are - root dir is aufs mount - unmount the root dir (actually remount as read-only) If I send you another patch, kindly would you test it? J. R. Okajima

peabee · 2022-03-07T23:41:40Z

# cat DOTconfig-5.16.12-lxpup64 | grep AUFS
CONFIG_AUFS_FS=y
CONFIG_AUFS_BRANCH_MAX_127=y
# CONFIG_AUFS_BRANCH_MAX_511 is not set
# CONFIG_AUFS_BRANCH_MAX_1023 is not set
# CONFIG_AUFS_BRANCH_MAX_32767 is not set
CONFIG_AUFS_SBILIST=y
CONFIG_AUFS_HNOTIFY=y
CONFIG_AUFS_HFSNOTIFY=y
CONFIG_AUFS_EXPORT=y
CONFIG_AUFS_INO_T_64=y
CONFIG_AUFS_XATTR=y
# CONFIG_AUFS_FHSM is not set
# CONFIG_AUFS_RDU is not set
# CONFIG_AUFS_DIRREN is not set
# CONFIG_AUFS_SHWH is not set
# CONFIG_AUFS_BR_RAMFS is not set
# CONFIG_AUFS_BR_FUSE is not set
# CONFIG_AUFS_BR_HFSPLUS is not set
CONFIG_AUFS_BDEV_LOOP=y
# CONFIG_AUFS_DEBUG is not set

CONFIG_AUFS_DEBUG is not set

If I send you another patch, kindly would you test it?

Certainly

sfjro · 2022-03-09T00:15:35Z

PB:

**CONFIG_AUFS_DEBUG is not set**

OK, thanx.

> If I send you another patch, kindly would you test it? Certainly

I was going to send you more debugging patch, but I still don't understand why my first patch didn't solve the problem. It was a one-liner patch, replacing "while (1)" by "while (src)". I have simulated your case by chroot, and succeeded reproducing the problem. And the one-liner patch solved the problem. But not on your side. I can't understand the situation. So shamelessly I'd ask you again try the first one-liner patch please. J. R. Okajima

peabee · 2022-03-09T09:39:48Z

And the one-liner patch solved the problem.
But not on your side. I can't understand the situation. So shamelessly
I'd ask you again try the first one-liner patch please.

Dear @sfjro
My sincere apologies - I do not know what happened but I must not have applied the one-liner patch correctly somehow!!!

I can confirm, following a rebuild, that 5.6.12, with the one-liner patch, does NOT crash.

Very sorry to have confused matters
Regards
@peabee

sfjro · 2022-03-09T12:16:04Z

PB:

I can confirm, following a rebuild, that 5.6.12, with the one-liner patch, does **NOT** crash. Very sorry to have confused matters

Thank you very much for your tests several times. Now I can see the bug scenario clearly, and my sleepless nights end today. :-) J. R. Okajima

The parameter "void *data" is NULL in unmounting. Reported-by: PB on github Signed-off-by: J. R. Okajima <hooanon05g@gmail.com> See-also: sfjro/aufs-standalone#9

sfjro · 2022-03-14T03:33:55Z

------- Blind-Carbon-Copy From: "J. R. Okajima" ***@***.***> To: ***@***.*** Cc: ***@***.*** Subject: aufs5 GIT release (v5.17-rc7) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: ***@***.***> Date: Mon, 14 Mar 2022 12:33:48 +0900 Message-ID: ***@***.***> o bugfix - - umount passes NULL to ->parse_monolithic(), reported by PB. J. R. Okajima - ---------------------------------------- - - aufs5-linux.git aufs: bugfix, umount passes NULL to ->parse_monolithic() - - aufs5-standalone.git Addition to above, aufs stdalone: cosmetic, missing copyright sentence - - aufs-util.git Nothing

…

------- End of Blind-Carbon-Copy

commit 25f5c5fdcb1b6c2a47f58b59c74547538b7b7c2a aufs5-standalone upstream. The parameter "void *data" is NULL in unmounting. Reported-by: PB on github Signed-off-by: J. R. Okajima <hooanon05g@gmail.com> See-also: sfjro/aufs-standalone#9 Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

peabee changed the title ~~kernel 5.16.12 issue with /mnt/sdc1/kernels/5.16/kernel-kit/aufs_sources/fs/aufs/fsctx.c~~ kernel 5.16.12 issue with /aufs/fsctx.c Mar 6, 2022

peabee changed the title ~~kernel 5.16.12 issue with /aufs/fsctx.c~~ kernel 5.16.12 & 5.15.25 issue with /aufs/fsctx.c Mar 6, 2022

peabee changed the title ~~kernel 5.16.12 & 5.15.25 issue with /aufs/fsctx.c~~ kernel 5.16.12 & 5.15.25 & 5.10.103 issue with /aufs/fsctx.c Mar 7, 2022

peabee closed this as completed Mar 10, 2022

peabee mentioned this issue Aug 15, 2023

230814 does not patch properly #30

Closed

sfjro mentioned this issue Oct 13, 2024

patching file mm/mmap.c fails for kernel 6.11.3 #47

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kernel 5.16.12 & 5.15.25 & 5.10.103 issue with /aufs/fsctx.c #9

kernel 5.16.12 & 5.15.25 & 5.10.103 issue with /aufs/fsctx.c #9

peabee commented Mar 6, 2022 •

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sfjro commented Mar 14, 2022 via email

kernel 5.16.12 & 5.15.25 & 5.10.103 issue with /aufs/fsctx.c #9

kernel 5.16.12 & 5.15.25 & 5.10.103 issue with /aufs/fsctx.c #9

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