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 68E3E2F9D85; Thu, 28 May 2026 20:46:38 +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=1780001199; cv=none; b=SaOPuszDsuji4QNU3UhqjPH5nCPdokCLQ1V6zymWIfr1IXrknqBKOHNpPMCgKRM78zUdiLF/Qs25fOJcytSxWKeOhFAf1dS+n6IZN7p+Fx6vyIDuMHQBVeC8NFVbNx35CZpDEToX+TKtk3C5U/i9Dab1V/8mR/NcY4y9AhGCNcY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780001199; c=relaxed/simple; bh=+m2Pl/o51lv9PhYg2WLz4z2WWH24BmofUOx6n40ibLc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lHtrNOjTPUiTJoYd7LGt53qGT6zM/3SHfjm0W5RRErZ3lPYDkJ3WvbdUv0r0jpmQATo51ixgz7sYfy3PPvhfctT26krRcNiy1qDvPgiKXykzUC9/ZJTndmHXN40rcwMmOVALzfCdlxSUvsEywhl9TeGfRMoWiXHkTc0d4fORnJ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ivMP+H2j; 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="ivMP+H2j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C731C1F00A3A; Thu, 28 May 2026 20:46:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780001198; bh=0WOtDTKnhjIqPR+RtdkwH5hi3mnFEckIG+7KBTMyJ8w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ivMP+H2jYmTVFIAMjmADBbf82TIv5KCcl3KGw3JxPfm1nrFNuE25aeySppOubjnCX 6VgqSeNAgAauEZMyV2tKwCD5O5JhUkbBDiVl8DA6acz4HyvzoKhRC1N79mcX/pqX66 zkS+B2ZHnHc2J0P3rO/B3sqdTDUWqEnJGMskptCg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ferry Meng , Namjae Jeon , Steve French Subject: [PATCH 6.6 025/186] ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow Date: Thu, 28 May 2026 21:48:25 +0200 Message-ID: <20260528194929.639215138@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194928.941004471@linuxfoundation.org> References: <20260528194928.941004471@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ferry Meng commit af92ee994cc7f7e83a41c2025f32257a2f82a7ef upstream. Commit 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") added check_add_overflow() guards that break out of the ACE-building loops in set_posix_acl_entries_dacl() when the accumulated DACL size would wrap past 65535. However, each iteration allocates a struct smb_sid via kmalloc_obj() at the top of the loop and relies on the kfree(sid) call at the end of the loop body (the 'pass_same_sid' label in the first loop, and the explicit kfree at the tail of the second loop) to release it. The newly introduced 'break' statements bypass those kfree() calls, leaking the sid buffer every time an overflow is detected. A malicious or malformed file with enough POSIX ACL entries to trip the overflow check will leak one or more struct smb_sid allocations on every request that touches the file's DACL, providing a trivial kernel memory exhaustion vector. Free sid before breaking out of the loops to plug the leak. Fixes: 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") Cc: stable@vger.kernel.org Signed-off-by: Ferry Meng Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/smbacl.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c index c1d1f34581d6..9161e9d7ed24 100644 --- a/fs/smb/server/smbacl.c +++ b/fs/smb/server/smbacl.c @@ -643,8 +643,10 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, ntace = (struct smb_ace *)((char *)pndace + *size); ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, flags, pace->e_perm, 0777); - if (check_add_overflow(*size, ace_sz, size)) + if (check_add_overflow(*size, ace_sz, size)) { + kfree(sid); break; + } (*num_aces)++; if (pace->e_tag == ACL_USER) ntace->access_req |= @@ -655,8 +657,10 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, ntace = (struct smb_ace *)((char *)pndace + *size); ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x03, pace->e_perm, 0777); - if (check_add_overflow(*size, ace_sz, size)) + if (check_add_overflow(*size, ace_sz, size)) { + kfree(sid); break; + } (*num_aces)++; if (pace->e_tag == ACL_USER) ntace->access_req |= @@ -698,8 +702,10 @@ posix_default_acl: ntace = (struct smb_ace *)((char *)pndace + *size); ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x0b, pace->e_perm, 0777); - if (check_add_overflow(*size, ace_sz, size)) + if (check_add_overflow(*size, ace_sz, size)) { + kfree(sid); break; + } (*num_aces)++; if (pace->e_tag == ACL_USER) ntace->access_req |= -- 2.54.0