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[2403:580d:fda1:0:2bb5:f164:6e6a:38d8]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-36f6bf8284dsm14033699a91.4.2026.06.06.23.12.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 06 Jun 2026 23:13:08 -0700 (PDT) Message-ID: Date: Sun, 7 Jun 2026 15:42:52 +0930 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] btrfs: lzo: reject compressed segment that overflows the compressed input To: Weiming Shi , David Sterba , Chris Mason Cc: Xiang Mei , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260607052511.4131138-3-bestswngs@gmail.com> Content-Language: en-US From: Qu Wenruo Autocrypt: addr=wqu@suse.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNGFF1IFdlbnJ1byA8d3F1QHN1c2UuY29tPsLAlAQTAQgAPgIbAwULCQgHAgYVCAkKCwIE FgIDAQIeAQIXgBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXVgBQkQ/lqxAAoJEMI9kfOh Jf6o+jIH/2KhFmyOw4XWAYbnnijuYqb/obGae8HhcJO2KIGcxbsinK+KQFTSZnkFxnbsQ+VY fvtWBHGt8WfHcNmfjdejmy9si2jyy8smQV2jiB60a8iqQXGmsrkuR+AM2V360oEbMF3gVvim 2VSX2IiW9KERuhifjseNV1HLk0SHw5NnXiWh1THTqtvFFY+CwnLN2GqiMaSLF6gATW05/sEd V17MdI1z4+WSk7D57FlLjp50F3ow2WJtXwG8yG8d6S40dytZpH9iFuk12Sbg7lrtQxPPOIEU rpmZLfCNJJoZj603613w/M8EiZw6MohzikTWcFc55RLYJPBWQ+9puZtx1DopW2jOwE0EWdWB rwEIAKpT62HgSzL9zwGe+WIUCMB+nOEjXAfvoUPUwk+YCEDcOdfkkM5FyBoJs8TCEuPXGXBO Cl5P5B8OYYnkHkGWutAVlUTV8KESOIm/KJIA7jJA+Ss9VhMjtePfgWexw+P8itFRSRrrwyUf E+0WcAevblUi45LjWWZgpg3A80tHP0iToOZ5MbdYk7YFBE29cDSleskfV80ZKxFv6koQocq0 vXzTfHvXNDELAuH7Ms/WJcdUzmPyBf3Oq6mKBBH8J6XZc9LjjNZwNbyvsHSrV5bgmu/THX2n g/3be+iqf6OggCiy3I1NSMJ5KtR0q2H2Nx2Vqb1fYPOID8McMV9Ll6rh8S8AEQEAAcLAfAQY AQgAJgIbDBYhBC3fcuWlpVuonapC4cI9kfOhJf6oBQJnEXWBBQkQ/lrSAAoJEMI9kfOhJf6o cakH+QHwDszsoYvmrNq36MFGgvAHRjdlrHRBa4A1V1kzd4kOUokongcrOOgHY9yfglcvZqlJ qfa4l+1oxs1BvCi29psteQTtw+memmcGruKi+YHD7793zNCMtAtYidDmQ2pWaLfqSaryjlzR /3tBWMyvIeWZKURnZbBzWRREB7iWxEbZ014B3gICqZPDRwwitHpH8Om3eZr7ygZck6bBa4MU o1XgbZcspyCGqu1xF/bMAY2iCDcq6ULKQceuKkbeQ8qxvt9hVxJC2W3lHq8dlK1pkHPDg9wO JoAXek8MF37R8gpLoGWl41FIUb3hFiu3zhDDvslYM4BmzI18QgQTQnotJH8= In-Reply-To: <20260607052511.4131138-3-bestswngs@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/6/7 14:55, Weiming Shi 写道: > lzo_decompress_bio() validates each on-disk segment length seg_len only > against the workspace cbuf size, not against the compressed input size > (compressed_len, the total folio bytes of the bio). A crafted extent can > carry a segment whose seg_len passes the cbuf check but runs past the end > of the bio, so copy_compressed_segment() walks off the last folio: > get_current_folio() then returns the NULL folio from bio_next_folio(), and > with CONFIG_BTRFS_ASSERT disabled (default) folio_size(NULL) faults. > > BUG: KASAN: null-ptr-deref in lzo_decompress_bio (fs/btrfs/lzo.c:383) > Read of size 8 at addr 0000000000000000 by task kworker/u8:1/29 > Workqueue: btrfs-endio simple_end_io_work > kasan_report (mm/kasan/report.c:590) > lzo_decompress_bio (fs/btrfs/lzo.c:383) > end_bbio_compressed_read (fs/btrfs/compression.c:1065) > btrfs_bio_end_io (fs/btrfs/bio.c:135) > btrfs_check_read_bio (fs/btrfs/bio.c:180 fs/btrfs/bio.c:285) > simple_end_io_work > process_one_work > worker_thread > > Reject any segment whose payload would extend beyond compressed_len before > copying it, treating it as corruption like the other on-disk validation > failures in this function. > > Fixes: a6e66e6f8c1b ("btrfs: rework lzo_decompress_bio() to make it subpage compatible") > Reported-by: Xiang Mei > Assisted-by: Claude:claude-opus-4-8 > Signed-off-by: Weiming Shi Reviewed-by: Qu Wenruo And pushed to for-next. Thanks, Qu > --- > v2: > - Return -EUCLEAN instead of -EIO to match lzo_decompress() (Qu Wenruo). > - Emit a btrfs_err() message when rejecting the segment (Qu Wenruo). > > fs/btrfs/lzo.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c > index 2de18c7b5..6e4aa2285 100644 > --- a/fs/btrfs/lzo.c > +++ b/fs/btrfs/lzo.c > @@ -491,6 +491,17 @@ int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) > return -EIO; > } > > + /* The segment must not extend beyond the compressed input. */ > + if (unlikely(cur_in + seg_len > compressed_len)) { > + struct btrfs_inode *inode = cb->bbio.inode; > + > + btrfs_err(fs_info, > + "lzo segment overflows compressed input, root %llu inode %llu offset %llu cur_in %u len %u compressed len %u", > + btrfs_root_id(inode->root), btrfs_ino(inode), > + cb->start, cur_in, seg_len, compressed_len); > + return -EUCLEAN; > + } > + > /* Copy the compressed segment payload into workspace */ > copy_compressed_segment(cb, &fi, &cur_folio_index, workspace->cbuf, > seg_len, &cur_in);