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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Sasha Levin <sashal@kernel.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
	kernel test robot <oliver.sang@intel.com>,
	Eric Biggers <ebiggers@kernel.org>,
	Andreas Dilger <adilger@dilger.ca>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Jason Donenfeld <Jason@zx2c4.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org
Subject: Re: [PATCH AUTOSEL 6.1 35/35] ext4: deal with legacy signed xattr name hash values
Date: Tue, 24 Jan 2023 09:23:56 -0800	[thread overview]
Message-ID: <CAHk-=wi5GPS3poC_YRy93X38AqkvsFENAviMXHWjgOgo5k7p3g@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wjZmzuHP10Trg_7EBnix4mFLfODPM+FsZz0Jjj+YAFDeg@mail.gmail.com>

[-- Attachment #1: Type: text/plain, Size: 828 bytes --]

On Tue, Jan 24, 2023 at 8:50 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> This patch does not work correctly without '-funsigned-char', and I
> don't think that has been back-ported to stable kernels.
>
> That said, the patch *almost* works.

So I'm  not convinced this should be back-ported at all, but it's
certainly true that going back and forth between the two cases would
be problematic.

Maybe the right thing to do would be for me to just do that explicit
'unsigned char' even in kernels that don't need it, and also add a
'pr_warn_once()' to make people aware of this case if it ever happens
outside of the xfstests.

So a more complete patch might be something like the attached (which
also changes the polarity of the signed hash test, in order to make
the pr_warn_once() simpler).

            Linus

[-- Attachment #2: patch.diff --]
[-- Type: text/x-patch, Size: 1026 bytes --]

 fs/ext4/xattr.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 69a1b8c6a2ec..a2f04a3808db 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -482,11 +482,12 @@ ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
 		 */
 		e_hash = ext4_xattr_hash_entry_signed(entry->e_name, entry->e_name_len,
 							&tmp_data, 1);
-		if (e_hash == entry->e_hash)
-			return 0;
-
 		/* Still no match - bad */
-		return -EFSCORRUPTED;
+		if (e_hash != entry->e_hash)
+			return -EFSCORRUPTED;
+
+		/* Let people know about old hash */
+		pr_warn_once("ext4: filesystem with signed xattr name hash");
 	}
 	return 0;
 }
@@ -3096,7 +3097,7 @@ static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
 	while (name_len--) {
 		hash = (hash << NAME_HASH_SHIFT) ^
 		       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
-		       *name++;
+		       (unsigned char)*name++;
 	}
 	while (value_count--) {
 		hash = (hash << VALUE_HASH_SHIFT) ^

  reply	other threads:[~2023-01-24 17:24 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-24 13:40 [PATCH AUTOSEL 6.1 01/35] ARM: dts: imx: Fix pca9547 i2c-mux node name Sasha Levin
2023-01-24 13:40 ` [PATCH AUTOSEL 6.1 02/35] ARM: dts: vf610: Fix pca9548 i2c-mux node names Sasha Levin
2023-01-24 13:40 ` [PATCH AUTOSEL 6.1 03/35] arm64: dts: freescale: Fix pca954x " Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 04/35] arm64: dts: imx8mq-thor96: fix no-mmc property for SDHCI Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 05/35] firmware: arm_scmi: Clear stale xfer->hdr.status Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 06/35] bpf: Skip task with pid=1 in send_signal_common() Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 07/35] erofs/zmap.c: Fix incorrect offset calculation Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 08/35] mac80211: Fix MLO address translation for multiple bss case Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 09/35] arm64: dts: msm8994-angler: fix the memory map Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 10/35] ARM: omap1: fix building gpio15xx Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 11/35] init/Kconfig: fix LOCALVERSION_AUTO help text Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 12/35] kselftest: Fix error message for unconfigured LLVM builds Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 13/35] erofs: clean up parsing of fscache related options Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 14/35] btrfs: factor out scratching of one regular super block Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 15/35] btrfs: stop using write_one_page in btrfs_scratch_superblock Sasha Levin
2023-01-24 16:57   ` David Sterba
2023-02-01 15:21     ` Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 16/35] blk-cgroup: fix missing pd_online_fn() while activating policy Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 17/35] LoongArch: Get frame info in unwind_start() when regs is not available Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 18/35] ACPI: video: Add backlight=native DMI quirk for Acer Aspire 4810T Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 19/35] block: fix hctx checks for batch allocation Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 20/35] s390: workaround invalid gcc-11 out of bounds read warning Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 21/35] HID: uclogic: Add support for XP-PEN Deco 01 V2 Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 22/35] HID: playstation: sanity check DualSense calibration data Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 23/35] dmaengine: imx-sdma: Fix a possible memory leak in sdma_transfer_init Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 24/35] gpiolib: acpi: Allow ignoring wake capability on pins that aren't in _AEI Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 25/35] cifs: fix return of uninitialized rc in dfs_cache_update_tgthint() Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 26/35] nvme-apple: only reset the controller when RTKit is running Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 27/35] octeontx2-af: recover CPT engine when it gets fault Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 28/35] octeontx2-af: add mbox for CPT LF reset Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 29/35] octeontx2-af: modify FLR sequence for CPT Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 30/35] octeontx2-af: optimize cpt pf identification Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 31/35] octeontx2-af: restore rxc conf after teardown sequence Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 32/35] octeontx2-af: update cpt lf alloc mailbox Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 33/35] octeontx2-af: add mbox to return CPT_AF_FLT_INT info Sasha Levin
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 34/35] prlimit: do_prlimit needs to have a speculation check Sasha Levin
2023-01-24 15:28   ` Greg Kroah-Hartman
2023-01-24 13:41 ` [PATCH AUTOSEL 6.1 35/35] ext4: deal with legacy signed xattr name hash values Sasha Levin
2023-01-24 16:50   ` Linus Torvalds
2023-01-24 17:23     ` Linus Torvalds [this message]
2023-01-25 16:01       ` Theodore Ts'o
2023-01-26 14:12         ` Sasha Levin

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