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([110.9.142.4]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3341be2073dsm10251836a91.19.2025.09.26.18.52.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Sep 2025 18:52:56 -0700 (PDT) From: Sang-Heon Jeon To: phillip@squashfs.org.uk Cc: linux-kernel@vger.kernel.org, Sang-Heon Jeon , syzbot+f754e01116421e9754b9@syzkaller.appspotmail.com, Amir Goldstein Subject: [PATCH] squashfs: add sanity check for invalid inode size Date: Sat, 27 Sep 2025 10:52:47 +0900 Message-ID: <20250927015247.957452-1-ekffu200098@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Corrupted squashfs images can have negative inode sizes. Add sanity check to prevent negative inode size. Reported-by: syzbot+f754e01116421e9754b9@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Df754e01116421e9754b9 Signed-off-by: Sang-Heon Jeon Tested-by: syzbot+f754e01116421e9754b9@syzkaller.appspotmail.com Cc: Amir Goldstein --- Special thanks to Amir's kindness analysis [1]. I couldn't find proper tag for credit, so i just cc-ing. But feel free to add proper credit. Also, I referred method of erofs. but i might be wrong, please let me know about that. Thanks for consideration. [1] https://lore.kernel.org/all/CAOQ4uxgkpi4v3NTSTq5GGJEceHHi97iY4rtsAJuo5c= -yxu-Bzg@mail.gmail.com/ --- fs/squashfs/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c index ddc65d006063..148cd75f5bd7 100644 --- a/fs/squashfs/inode.c +++ b/fs/squashfs/inode.c @@ -426,6 +426,12 @@ int squashfs_read_inode(struct inode *inode, long long= ino) return -EINVAL; } =20 + if (unlikely(inode->i_size < 0)) { + ERROR("Negative i_size %lld inode 0x%llx\n", + inode->i_size, ino); + return -EINVAL; + } + if (xattr_id !=3D SQUASHFS_INVALID_XATTR && msblk->xattr_id_table) { err =3D squashfs_xattr_lookup(sb, xattr_id, &squashfs_i(inode)->xattr_count, --=20 2.43.0