Commit 93a26966 authored by David Howells's avatar David Howells Committed by sanglipeng1
Browse files

afs: Fix endless loop in directory parsing 

stable inclusion
from stable-v5.10.212
commit 96370ba395c572ef496fd2c7afc4a1ab3dedd3f0
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAGOP2

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=96370ba395c572ef496fd2c7afc4a1ab3dedd3f0

--------------------------------

[ Upstream commit 5f7a07646655fb4108da527565dcdc80124b14c4 ]

If a directory has a block with only ".__afsXXXX" files in it (from
uncompleted silly-rename), these .__afsXXXX files are skipped but without
advancing the file position in the dir_context.  This leads to
afs_dir_iterate() repeating the block again and again.

Fix this by making the code that skips the .__afsXXXX file also manually
advance the file position.

The symptoms are a soft lookup:

        watchdog: BUG: soft lockup - CPU#3 stuck for 52s! [check:5737]
        ...
        RIP: 0010:afs_dir_iterate_block+0x39/0x1fd
        ...
         ? watchdog_timer_fn+0x1a6/0x213
        ...
         ? asm_sysvec_apic_timer_interrupt+0x16/0x20
         ? afs_dir_iterate_block+0x39/0x1fd
         afs_dir_iterate+0x10a/0x148
         afs_readdir+0x30/0x4a
         iterate_dir+0x93/0xd3
         __do_sys_getdents64+0x6b/0xd4

This is almost certainly the actual fix for:

        https://bugzilla.kernel.org/show_bug.cgi?id=218496



Fixes: 57e9d49c5452 ("afs: Hide silly-rename files from userspace")
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/786185.1708694102@warthog.procyon.org.uk


Reviewed-by: default avatarMarc Dionne <marc.dionne@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Markus Suvanto <markus.suvanto@gmail.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarsanglipeng1 <sanglipeng1@jd.com>
parent bf313fff

fs/afs/dir.c

+3 −1
Original line number Diff line number Diff line
@@ -423,8 +423,10 @@ static int afs_dir_iterate_block(struct afs_vnode *dvnode, 
		    dire->u.name[0] == '.' &&

		    ctx->actor != afs_lookup_filldir &&

		    ctx->actor != afs_lookup_one_filldir &&

		    memcmp(dire->u.name, ".__afs", 6) == 0)

		    memcmp(dire->u.name, ".__afs", 6) == 0) {

			ctx->pos = blkoff + next * sizeof(union afs_xdr_dirent);

			continue;

		}



		/* found the next entry */

		if (!dir_emit(ctx, dire->u.name, nlen,