From nobody Thu Apr 9 15:44:36 2026 Received: from mail-oa1-f70.google.com (mail-oa1-f70.google.com [209.85.160.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5756F14E2F2 for ; Sat, 7 Mar 2026 00:25:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.70 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772843124; cv=none; b=paBTgPYRxSm5AAc7RlIA2mcMJrweVlgRa17goEQnpN58xAx48JFOLjf8BDy3nypzEbNR1qtmJPIKPBEoGL3E5vDIBbIR/TF//E0tCZU1YpRTcuus1IOm88Cc936nY04yiIzUfyvRmQk3sdtkrkCTco1zrjpW2ZG5EYCBvbfYYPk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772843124; c=relaxed/simple; bh=jucgNUGtTLlFQrnhnJSN5iPQBMs7noVoemqWUIG1e5o=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=IaceenbsZR/DpOCcreySR+YNXQGeL8iBLyEwyLBEwVKeSE9nuECI0D3VU3MW4pxc/sZ+aUy74WwAlfFNcYbvFQfLOsvKGPYSq34cRGKj3VafOFaCzZIBAdc59eKDg8bnhMlAT/Ax7uwCJVUsYNYGpRcs2KPFDG7HryGkIELYNFI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.160.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oa1-f70.google.com with SMTP id 586e51a60fabf-40948b7e832so47849241fac.0 for ; Fri, 06 Mar 2026 16:25:23 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772843122; x=1773447922; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=i0LITG9mBCwrRPRVaqnXc+dNX5vY1+3PzBjZECM5rdE=; b=OPiYfpcbRuLwEEVE9qmI/ZwFXqJa6kz3CopVEZEAAuAj7hZrpHSGgCtvA0mOfoig73 MwE/5ktKg382HOj4g+XRFmFCMtVUxtHzkWO70SqUcSG6zMRGYV8qgmQKoHR0VL1GyMAG +u9/h6m5fWW8iyGLHgU4Rc3kPzH2JhrGnUtuMUbc2P1e6wyiykRX9UhpwIcKcV7G7zS1 kURT91Ah8JPINqREhDp934q+9SH3U1pLrmNmaM7BZR4AVYup+k9oXaNW0P2XvjJoAwxc nnSUUExvGLbwgUXk7RnI8MV8Wi247+Gq9s2zDg4Fwpap1aLnlAjtZkvbzw8dj2sXUPBU eATA== X-Gm-Message-State: AOJu0YzGirgBsiNAARp8QD5BTp4nrOQRjvGO8vvPUw6QFm9x9RsE0x96 U4W+rg0pnHDAfXcAcdL7NUa1+d7fHgq+wCWBJ5I702AINdN9IS9m5IZY2FVzJhZvrgLnMsyVGvy Fyifa6TNj7jMdMZu5j3WDWd7lAygB2d6fPjICfX37tU/hIggZBxhvaxUpeRE= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:488e:b0:67a:1d88:46cd with SMTP id 006d021491bc7-67b9bca17a3mr2117586eaf.23.1772843122353; Fri, 06 Mar 2026 16:25:22 -0800 (PST) Date: Fri, 06 Mar 2026 16:25:22 -0800 In-Reply-To: <696ea368.a70a0220.34546f.04b7.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69ab7072.050a0220.13f275.0031.GAE@google.com> Subject: Forwarded: [PATCH v6] hfsplus: fix uninit-value by validating catalog record size From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: [PATCH v6] hfsplus: fix uninit-value by validating catalog record = size Author: kartikey406@gmail.com #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git= master Syzbot reported a KMSAN uninit-value issue in hfsplus_strcasecmp(). The root cause is that hfs_brec_read() doesn't validate that the on-disk record size matches the expected size for the record type being read. When mounting a corrupted filesystem, hfs_brec_read() may read less data than expected. For example, when reading a catalog thread record, the debug output showed: HFSPLUS_BREC_READ: rec_len=3D520, fd->entrylength=3D26 HFSPLUS_BREC_READ: WARNING - entrylength (26) < rec_len (520) - PARTIAL R= EAD! hfs_brec_read() only validates that entrylength is not greater than the buffer size, but doesn't check if it's less than expected. It successfully reads 26 bytes into a 520-byte structure and returns success, leaving 494 bytes uninitialized. This uninitialized data in tmp.thread.nodeName then gets copied by hfsplus_cat_build_key_uni() and used by hfsplus_strcasecmp(), triggering the KMSAN warning when the uninitialized bytes are used as array indices in case_fold(). Fix by introducing hfsplus_brec_read_cat() wrapper that: 1. Calls hfs_brec_read() to read the data 2. Validates the record size based on the type field: - Fixed size for folder and file records - Variable size for thread records (depends on string length) 3. Returns -EIO if size doesn't match expected For thread records, check against HFSPLUS_MIN_THREAD_SZ before reading nodeName.length to avoid reading uninitialized data at call sites that don't zero-initialize the entry structure. Also initialize the tmp variable in hfsplus_find_cat() as defensive programming to ensure no uninitialized data even if validation is bypassed. Reported-by: syzbot+d80abb5b890d39261e72@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dd80abb5b890d39261e72 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Tested-by: syzbot+d80abb5b890d39261e72@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/20260120051114.1281285-1-kartikey406@gmai= l.com/ [v1] Link: https://lore.kernel.org/all/20260121063109.1830263-1-kartikey406@gmai= l.com/ [v2] Link: https://lore.kernel.org/all/20260212014233.2422046-1-kartikey406@gmai= l.com/ [v3] Link: https://lore.kernel.org/all/20260214002100.436125-1-kartikey406@gmail= .com/T/ [v4] Link: https://lore.kernel.org/all/20260221061626.15853-1-kartikey406@gmail.= com/T/ [v5] Signed-off-by: Deepanshu Kartikey --- Changes in v6: - Use HFSPLUS_MIN_THREAD_SZ constant instead of offsetof() calculation for thread record size check, as suggested by Charalampos Mitrodimas Changes in v5: - Add minimum size check for thread records before reading nodeName.length to avoid reading uninitialized data Changes in v4: - Move hfsplus_cat_thread_size() as static inline to header file Changes in v3: - Introduced hfsplus_brec_read_cat() wrapper function for catalog-specific validation instead of modifying generic hfs_brec_read() - Added hfsplus_cat_thread_size() helper to calculate variable-size thread record sizes - Use exact size match (!=3D) instead of minimum size check (<) - Use sizeof(hfsplus_unichr) instead of hardcoded value 2 - Updated all catalog record read sites to use new wrapper function Changes in v2: - Use structure initialization (=3D {0}) instead of memset() - Improved commit message to clarify how uninitialized data is used --- fs/hfsplus/bfind.c | 51 +++++++++++++++++++++++++++++++++++++++++ fs/hfsplus/catalog.c | 4 ++-- fs/hfsplus/dir.c | 2 +- fs/hfsplus/hfsplus_fs.h | 9 ++++++++ fs/hfsplus/super.c | 2 +- 5 files changed, 64 insertions(+), 4 deletions(-) diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c index 336d654861c5..9a55fa6d5294 100644 --- a/fs/hfsplus/bfind.c +++ b/fs/hfsplus/bfind.c @@ -287,3 +287,54 @@ int hfs_brec_goto(struct hfs_find_data *fd, int cnt) fd->bnode =3D bnode; return res; } + +/** + * hfsplus_brec_read_cat - read and validate a catalog record + * @fd: find data structure + * @entry: pointer to catalog entry to read into + * + * Reads a catalog record and validates its size matches the expected + * size based on the record type. + * + * Returns 0 on success, or negative error code on failure. + */ +int hfsplus_brec_read_cat(struct hfs_find_data *fd, hfsplus_cat_entry *ent= ry) +{ + int res; + u32 expected_size; + + res =3D hfs_brec_read(fd, entry, sizeof(hfsplus_cat_entry)); + if (res) + return res; + + /* Validate catalog record size based on type */ + switch (be16_to_cpu(entry->type)) { + case HFSPLUS_FOLDER: + expected_size =3D sizeof(struct hfsplus_cat_folder); + break; + case HFSPLUS_FILE: + expected_size =3D sizeof(struct hfsplus_cat_file); + break; + case HFSPLUS_FOLDER_THREAD: + case HFSPLUS_FILE_THREAD: + /* Ensure we have at least the fixed fields before reading nodeName.leng= th */ + if (fd->entrylength < HFSPLUS_MIN_THREAD_SZ) { + pr_err("thread record too short (got %u)\n", fd->entrylength); + return -EIO; + } + expected_size =3D hfsplus_cat_thread_size(&entry->thread); + break; + default: + pr_err("unknown catalog record type %d\n", + be16_to_cpu(entry->type)); + return -EIO; + } + + if (fd->entrylength !=3D expected_size) { + pr_err("catalog record size mismatch (type %d, got %u, expected %u)\n", + be16_to_cpu(entry->type), fd->entrylength, expected_size); + return -EIO; + } + + return 0; +} diff --git a/fs/hfsplus/catalog.c b/fs/hfsplus/catalog.c index 02c1eee4a4b8..6c8380f7208d 100644 --- a/fs/hfsplus/catalog.c +++ b/fs/hfsplus/catalog.c @@ -194,12 +194,12 @@ static int hfsplus_fill_cat_thread(struct super_block= *sb, int hfsplus_find_cat(struct super_block *sb, u32 cnid, struct hfs_find_data *fd) { - hfsplus_cat_entry tmp; + hfsplus_cat_entry tmp =3D {0}; int err; u16 type; =20 hfsplus_cat_build_key_with_cnid(sb, fd->search_key, cnid); - err =3D hfs_brec_read(fd, &tmp, sizeof(hfsplus_cat_entry)); + err =3D hfsplus_brec_read_cat(fd, &tmp); if (err) return err; =20 diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c index d559bf8625f8..25535592234c 100644 --- a/fs/hfsplus/dir.c +++ b/fs/hfsplus/dir.c @@ -49,7 +49,7 @@ static struct dentry *hfsplus_lookup(struct inode *dir, s= truct dentry *dentry, if (unlikely(err < 0)) goto fail; again: - err =3D hfs_brec_read(&fd, &entry, sizeof(entry)); + err =3D hfsplus_brec_read_cat(&fd, &entry); if (err) { if (err =3D=3D -ENOENT) { hfs_find_exit(&fd); diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h index 5f891b73a646..61d52091dd28 100644 --- a/fs/hfsplus/hfsplus_fs.h +++ b/fs/hfsplus/hfsplus_fs.h @@ -509,6 +509,15 @@ int hfsplus_submit_bio(struct super_block *sb, sector_= t sector, void *buf, void **data, blk_opf_t opf); int hfsplus_read_wrapper(struct super_block *sb); =20 +static inline u32 hfsplus_cat_thread_size(const struct hfsplus_cat_thread = *thread) +{ + return offsetof(struct hfsplus_cat_thread, nodeName) + + offsetof(struct hfsplus_unistr, unicode) + + be16_to_cpu(thread->nodeName.length) * sizeof(hfsplus_unichr); +} + +int hfsplus_brec_read_cat(struct hfs_find_data *fd, hfsplus_cat_entry *ent= ry); + /* * time helpers: convert between 1904-base and 1970-base timestamps * diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c index 7229a8ae89f9..5ef0f71b1a33 100644 --- a/fs/hfsplus/super.c +++ b/fs/hfsplus/super.c @@ -571,7 +571,7 @@ static int hfsplus_fill_super(struct super_block *sb, s= truct fs_context *fc) err =3D hfsplus_cat_build_key(sb, fd.search_key, HFSPLUS_ROOT_CNID, &str); if (unlikely(err < 0)) goto out_put_root; - if (!hfs_brec_read(&fd, &entry, sizeof(entry))) { + if (!hfsplus_brec_read_cat(&fd, &entry)) { hfs_find_exit(&fd); if (entry.type !=3D cpu_to_be16(HFSPLUS_FOLDER)) { err =3D -EIO; --=20 2.43.0