From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87B5046D565 for ; Wed, 29 Jul 2026 13:56:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785333370; cv=none; b=Wpy83konOMKPcdaq22q1vG/RNdiYbpL+RWJ5LbDauYC4noeGcZP9ai7NkXdkZa/eS8KK/piFouhhqdkkaI8F2Ul2HPYtjzhSqhj/64jn1VrcwrmTxC0vuors13ebOc9pDTpjM+7Eur/7rjXUXiGErjULpUo2NlRm9rn+krTg5aI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785333370; c=relaxed/simple; bh=pVr5G6QFH/REweba2mJiZ71B9cwuiI+ltplLKPjcSGc=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=t7wRqCuEa9XXgrSoQ16vnCRPEA3qtYtgWJb3wgPLbvoGyjRcR4GrQvDCAbMi61K6j9zc4XPSvL0Q0iKfFTJwzVhylWckWMc2fewAR4VBl+2vHjVLN+k/vJ2uZwOUzsagrCrHl82Q615n3eIX1184BcYhd7t6PNTsHvoe2vcxVZM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OagyxVu6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OagyxVu6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A95E01F00A3A; Wed, 29 Jul 2026 13:56:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785333366; bh=eY/gEqSt0ebQSRUM4LZIf0DK3IH60iAGaV7m4KlYkvs=; h=Subject:To:Cc:From:Date; b=OagyxVu6rCcnNR7L4em29JSrh7YZ8S6LERTHCXBaW+iLXpZ/YRV2uSSAiZo1LXX8Y c4fhzIgESTlvHjyrcPzuRghrHoCMyUG7zLPbdLH7ROfAN5QNUiyEIh6w5LPmwnGeBD XjcXncYDcjW+eqtzfdAJNjypWt4rcasMSxkwJvwA= Subject: FAILED: patch "[PATCH] ksmbd: restore DACL size on check_add_overflow() to avoid" failed to apply to 6.1-stable tree To: guanwentao@uniontech.com,linkinjeon@kernel.org,stfrench@microsoft.com Cc: From: Date: Wed, 29 Jul 2026 15:55:37 +0200 Message-ID: <2026072937-broadcast-renewal-0307@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x bbf0a8e931204ecdab494a88d43b0a24a04285c5 # git commit -s git send-email --to '' --in-reply-to '2026072937-broadcast-renewal-0307@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From bbf0a8e931204ecdab494a88d43b0a24a04285c5 Mon Sep 17 00:00:00 2001 From: Wentao Guan Date: Fri, 3 Jul 2026 11:22:09 +0900 Subject: [PATCH] ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL check_add_overflow() unconditionally writes the truncated sum into *d even on overflow, per its contract in include/linux/overflow.h. The four check_add_overflow() guards in set_posix_acl_entries_dacl() and set_ntacl_dacl() break out of the ACE-building loops on overflow, but the truncated *size is then consumed downstream at the end of set_ntacl_dacl(): pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size); This produces an on-wire NT ACL whose pndacl->size under-reports the bytes actually written by the preceding fill_ace_for_sid()/memcpy() calls, yielding a malformed ACL that can trigger out-of-bounds reads when re-parsed by clients or ksmbd itself. Restore *size to its pre-addition value on each overflow branch (via `*size -= ace_sz` / `size -= nt_ace_size`) so that after the break, *size once again holds the cumulative size of the successfully-written ACEs. The committed ACL is then truncated-but-self-consistent rather than malformed. The ksmbd DACL builders are the only check_add_overflow() sites found where an overflow path breaks out of a loop and the destination value is consumed afterward. The other nearby break-style cases either return -EINVAL on overflow (transport_ipc.c) or break without consuming the overflowed destination value afterward (buildid.c). Fixes: 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") Assisted-by: atomcode:glm-5.2 Assisted-by: Codex:gpt-5.5 Cc: stable@vger.kernel.org Signed-off-by: Wentao Guan Acked-by: Namjae Jeon Signed-off-by: Steve French diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c index d28289188e44..f285b4f24a5b 100644 --- a/fs/smb/server/smbacl.c +++ b/fs/smb/server/smbacl.c @@ -663,6 +663,7 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, flags, pace->e_perm, 0777); if (check_add_overflow(*size, ace_sz, size)) { + *size -= ace_sz; kfree(sid); break; } @@ -677,6 +678,7 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x03, pace->e_perm, 0777); if (check_add_overflow(*size, ace_sz, size)) { + *size -= ace_sz; kfree(sid); break; } @@ -722,6 +724,7 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x0b, pace->e_perm, 0777); if (check_add_overflow(*size, ace_sz, size)) { + *size -= ace_sz; kfree(sid); break; } @@ -765,8 +768,10 @@ static void set_ntacl_dacl(struct mnt_idmap *idmap, goto next_ace; memcpy((char *)pndace + size, ntace, nt_ace_size); - if (check_add_overflow(size, nt_ace_size, &size)) + if (check_add_overflow(size, nt_ace_size, &size)) { + size -= nt_ace_size; break; + } num_aces++; next_ace: