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b=xZ6Vzia7OeViQMNsNrs6M9U/QS4Ba5Wnm7fkdlElfQ0kaBJy8gNwpyn86XiT25s7Em5jGU O+vH7Mq9c2JfE7Dg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 24A7513941; Wed, 27 Nov 2024 06:35:45 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id S/R2M8G9RmfDCQAAD6G6ig (envelope-from ); Wed, 27 Nov 2024 06:35:45 +0000 Date: Wed, 27 Nov 2024 17:35:36 +1100 From: David Disseldorp To: linux-fsdevel@vger.kernel.org Cc: linux-kselftest@vger.kernel.org, Al Viro , Christian Brauner Subject: Re: [PATCH v3 8/9] initramfs: fix hardlink hash leak without TRAILER Message-ID: <20241127173536.76815a5b.ddiss@suse.de> In-Reply-To: <20241107002044.16477-10-ddiss@suse.de> References: <20241107002044.16477-1-ddiss@suse.de> <20241107002044.16477-10-ddiss@suse.de> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D47EB1F76C X-Spam-Level: X-Spamd-Result: default: False [-3.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ASN(0.00)[asn:25478, ipnet:::/0, country:RU]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; TO_DN_SOME(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -3.51 X-Spam-Flag: NO On Thu, 7 Nov 2024 11:17:27 +1100, David Disseldorp wrote: > Covered in Documentation/driver-api/early-userspace/buffer-format.rst , > initramfs archives can carry an optional "TRAILER!!!" entry which serves > as a boundary for collecting and associating hardlinks with matching > inode and major / minor device numbers. > > Although optional, if hardlinks are found in an archive without a > subsequent "TRAILER!!!" entry then the hardlink state hash table is > leaked One further leak is possible if extraction ends prior to fput(wfile) in CopyFile state, e.g. due to lack of data: nilchar="\0" data="123456789ABCDEF" magic="070701" ino=1 mode=$(( 0100777 )) uid=0 gid=0 nlink=1 mtime=1 filesize=$(( ${#data} + 20 )) # too much devmajor=0 devminor=1 rdevmajor=0 rdevminor=0 csum=0 fname="initramfs_test_archive_overrun" namelen=$(( ${#fname} + 1 )) # plus one to account for terminator printf "%s%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%s" \ $magic $ino $mode $uid $gid $nlink $mtime $filesize \ $devmajor $devminor $rdevmajor $rdevminor $namelen $csum $fname termpadlen=$(( 1 + ((4 - ((110 + $namelen) & 3)) % 4) )) printf "%.s${nilchar}" $(seq 1 $termpadlen) # $filesize reaches 20 bytes beyond end of data printf "%s" "$data" bash data_repro.sh|gzip >> initramfs unreferenced object 0xffff8fdb0192e000 (size 176): comm "kworker/u8:0", pid 11, jiffies 4294892503 hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 1e 80 5d 00 ..............]. 80 7d a1 a7 ff ff ff ff 10 b1 2f 02 db 8f ff ff .}......../..... backtrace (crc 807bd733): [<00000000e68e8b32>] kmem_cache_alloc_noprof+0x11e/0x260 [<00000000a6f24fcd>] alloc_empty_file+0x45/0x120 [<00000000130beec8>] path_openat+0x2f/0xf30 [<0000000024613ad7>] do_filp_open+0xa7/0x110 [<000000005f4f0158>] file_open_name+0x118/0x180 [<0000000003ed573f>] filp_open+0x27/0x50 [<0000000091ec9e44>] do_name+0xc4/0x2b0 [<000000008e084ec8>] write_buffer+0x22/0x40 [<000000002ea2ff4b>] flush_buffer+0x2f/0x90 [<000000009085f8b5>] gunzip+0x25a/0x310 [<000000000c1c83c3>] unpack_to_rootfs+0x176/0x2a0 [<00000000c966fda5>] do_populate_rootfs+0x6a/0x180 [<0000000051fb877d>] async_run_entry_fn+0x31/0x120 [<00000000a3ee305f>] process_scheduled_works+0xbe/0x310 [<0000000083c835bb>] worker_thread+0x100/0x240 [<000000006ea2f0b3>] kthread+0xc8/0x100 Not sure whether others are interested in seeing these kinds of leak-on-malformed-archive bugs fixed, but I'll send through a v4 with a fix + unit test for it.