From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f43.google.com (mail-ed1-f43.google.com [209.85.208.43]) (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 95009352C48 for ; Wed, 28 Jan 2026 13:24:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769606652; cv=none; b=DUoYMpkIalQ9D5JGNP1WUNni8iqDzXUTozS9uQ2thz9EJvajtryRWNJv7/FMP6AvJA6l+toqgB9/pbZUTDoAq3rMS8Cpue07HJY5nVr4GUg0UK5DBcR8m79bKeau4EO98h2oGyiRgfH+W8Io197+JTEkYCBmQNqcIPZfrnRf344= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769606652; c=relaxed/simple; bh=by5c7OBWmvzWhVys6tF6T+VYllXJ1/+r8xSpNq3nuBQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LtdrvhDHjX1FuDb1TXSif5XewDwUxIhJz4W/lQlySG36naqg6w1yORajhlsEY7tTuwGSkyqtXjvk10aHQa2lomr3p6vbdI3/VNLHi6ZtM2AaMnAbmU07pBMj8KB0TNGqZJK5O/OZLwy7VH+5JlxmNbW6qIuYWY8bKSdh51OF1so= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=W7nt6ktY; arc=none smtp.client-ip=209.85.208.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="W7nt6ktY" Received: by mail-ed1-f43.google.com with SMTP id 4fb4d7f45d1cf-658b5e57584so1810884a12.1 for ; Wed, 28 Jan 2026 05:24:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769606649; x=1770211449; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=kxRM277namVFNLdkVHTNF4KV4lqJB7EgGMx8/qf8f94=; b=W7nt6ktYD1RiYz7pLN3PILLQbdb08/u009q6bRnAlNJiVOEJHRL0t1SR22otnk1NOC R2+KUUGfOWhX931UJKyosaYw2rNAzzXfb+Wfo+bxZWeW2FQRLcIlBfSOyaIPZqrGLKtY Y9CEKp+y3CrTHht6gaBKb/4cprKUfaF4iFMbIi1kXePlPeTgFgZbPZvTKwwSuVH14EyW hzNK5NDI5N/QoOoVjPlcgLd06+aFpLLNX1nmV2mcfqynHEKWf53Hpg+ilU8gPxVP7LBZ J747uuQqwoxIUG9shomO9o5KIt1eP1a4GFNZaJ59P+5blXfNNIc+V8ZEGoKVbdsD3Ifw eBnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769606649; x=1770211449; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=kxRM277namVFNLdkVHTNF4KV4lqJB7EgGMx8/qf8f94=; b=I9Q15+vAnXoUoeIDNfaFvdPgvz/2mct9B1Sxzd4mVACJB8ZjEdicGH+ChMkpoaSiip GjgYlazrSY37oC36EjJ2+ZA/+TZyGhM0U5SSI6rnG35Q7leEaVj3sAky7Ly/uligxz6K Vp8nBkodE1hFiN7kye4cX44zz6+Jr8YWVnaNBeAc+4UeCEdM3n5jcOegoMf6ExJl+NP7 9ToSUWpi4E/dQ7FSHh8IfC89VDkBArjDr96zwRnbOHnRlUimLsYZ3jsvsxoKL/YAySbv 60QGASQ/83u8Wwy1AUgW+yQiVwFAizSuc2Volax82py77APzv9TrrHGGhGuGEdue/XG7 jJpQ== X-Forwarded-Encrypted: i=1; AJvYcCUggP1Y68HolpgCaDM/2OscPXnAdgLAPvGNjZrpTxZm0qvzgscLDTV6cnvheD15kNwJe7frqEseVVpM6aOz@vger.kernel.org X-Gm-Message-State: AOJu0Yx9CbRYsiNRqPuhdLhkWrbx+ONDsHaRpI2I94f6XHuKK3dVJH7z gE0Avra4eaLHDjPQGNErUdLw7PCW5x7qVQnmN/jdszosCib7j8AXObDt X-Gm-Gg: AZuq6aLfnkQJrNajSMxycL9WcE2ZTmhXx86gS26Zd3fkYV5rb8GmAmh1qWhvfaqZDXi Vof5UTY4JzkwwQn9VwVx6k1QhKWiQv86CgnHWfsYdCNcoawkzuAz859Uj3UxQIyHs7S+eTAhM2k ebed1VnL1YJBOsyqOu1pmkq+e6E6d8HMbZL3ABKoLALFZrfzAiisj3mEX/GL88O46baHa7ItjBc g0Y3QNkyfPbtXQ08aqNxPl90klxD78Yh5IloSSwky/5WxcoDBeb0ZClTCwNeq1T36NryhLZcA5n UEbT8CiLcKok8Xj7CKmz+e6Umm0/MBSD2iPVhpaG8ijfQLbUTHqR/D2PVblz0qP/l/I8M+S3d7k DWaq7jFwh68jHXecmGp4ukCGQaWNS4i0KfH+OHMQkhZgDVCETBRCRrcPfRjftgTSBimRnFtHskk g43nYlsHhDkT+254ezSj/Dc8RG/cR7ElzPTT8VZFXSvQBuupmmwJUUTNb9G1sAg8GAgpJMBIVrF 8jDML9xiBAEjmOnRLujxToVYmk= X-Received: by 2002:a17:907:6d0a:b0:b87:1c74:a8c6 with SMTP id a640c23a62f3a-b8dab3f022dmr389917666b.57.1769606648807; Wed, 28 Jan 2026 05:24:08 -0800 (PST) Received: from localhost (2001-1c00-570d-ee00-c84e-f30e-bdab-df5a.cable.dynamic.v6.ziggo.nl. [2001:1c00:570d:ee00:c84e:f30e:bdab:df5a]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b8dbf184343sm122306466b.33.2026.01.28.05.24.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jan 2026 05:24:08 -0800 (PST) From: Amir Goldstein To: Miklos Szeredi , Christian Brauner Cc: Qing Wang , linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com Subject: [PATCH 1/3] ovl: Fix uninit-value in ovl_fill_real Date: Wed, 28 Jan 2026 14:24:04 +0100 Message-ID: <20260128132406.23768-2-amir73il@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260128132406.23768-1-amir73il@gmail.com> References: <20260128132406.23768-1-amir73il@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Qing Wang Syzbot reported a KMSAN uninit-value issue in ovl_fill_real. This iusse's call chain is: __do_sys_getdents64() -> iterate_dir() ... -> ext4_readdir() -> fscrypt_fname_alloc_buffer() // alloc -> fscrypt_fname_disk_to_usr // write without tail '\0' -> dir_emit() -> ovl_fill_real() // read by strcmp() The string is used to store the decrypted directory entry name for an encrypted inode. As shown in the call chain, fscrypt_fname_disk_to_usr() write it without null-terminate. However, ovl_fill_real() uses strcmp() to compare the name against "..", which assumes a null-terminated string and may trigger a KMSAN uninit-value warning when the buffer tail contains uninit data. Reported-by: syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d130f98b2c265fae5297 Fixes: 4edb83bb1041 ("ovl: constant d_ino for non-merge dirs") Signed-off-by: Qing Wang Signed-off-by: Amir Goldstein --- fs/overlayfs/readdir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 160960bb0ad0b..724ec9d93fc82 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -755,7 +755,7 @@ static bool ovl_fill_real(struct dir_context *ctx, const char *name, struct dir_context *orig_ctx = rdt->orig_ctx; bool res; - if (rdt->parent_ino && strcmp(name, "..") == 0) { + if (rdt->parent_ino && namelen == 2 && !strncmp(name, "..", 2)) { ino = rdt->parent_ino; } else if (rdt->cache) { struct ovl_cache_entry *p; -- 2.52.0