FAILED: patch "[PATCH] smb: client: validate SMB1 EA list bounds before parsing" failed to apply to 5.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.10-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 <stable@vger.kernel.org>.

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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x ddc7a7e1eeb116ccaf010a6f1fb6ab927f3f888d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026110409-unsoiled-surging-adc6@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ddc7a7e1eeb116ccaf010a6f1fb6ab927f3f888d Mon Sep 17 00:00:00 2001
From: Ratnaker Gautam <ratnaker.gautam@kuleuven.be>
Date: Sat, 24 Oct 2026 12:36:14 +0000
Subject: [PATCH] smb: client: validate SMB1 EA list bounds before parsing

CIFSSMBQAllEAs() checks the server-provided EA list length by adding it
to the response pointer. On 32-bit systems, a positive length can wrap
the pointer and pass the comparison. The parser then walks outside the
received response while reading the next FEA header.

A response with a list length of 0x40000000 reproduces this as a native
i386 page fault and kernel panic from listxattr() against an SMB1
server.

Check that the EA list starts within the SMB byte area before reading
its header. Keep its length unsigned and compare it with the bytes left
in the response without pointer addition.

SMB1 is not negotiated by default and requires an explicit vers=1.0
mount.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Ratnaker Gautam <ratnaker.gautam@kuleuven.be>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>

diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index 9ffc94ac2069..2936b38de98f 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -6215,9 +6215,11 @@ CIFSSMBQAllEAs(const unsigned int xid, struct cifs_tcon *tcon,
 	int rc = 0;
 	int bytes_returned;
 	int list_len;
+	u32 ea_list_len;
 	struct fealist *ea_response_data;
 	struct fea *temp_fea;
 	char *temp_ptr;
+	char *byte_area;
 	char *end_of_smb;
 	__u16 params, byte_count, data_offset;
 	unsigned int ea_name_len = ea_name ? strlen(ea_name) : 0;
@@ -6296,9 +6298,19 @@ CIFSSMBQAllEAs(const unsigned int xid, struct cifs_tcon *tcon,
 	ea_response_data = (struct fealist *)
 				(((char *) &pSMBr->hdr.Protocol) + data_offset);
 
-	list_len = le32_to_cpu(ea_response_data->list_len);
-	cifs_dbg(FYI, "ea length %d\n", list_len);
-	if (list_len <= 8) {
+	byte_area = pByteArea(&pSMBr->hdr);
+	end_of_smb = byte_area + get_bcc(&pSMBr->hdr);
+	if ((char *)ea_response_data < byte_area ||
+	    (char *)ea_response_data >
+	    end_of_smb - sizeof(ea_response_data->list_len)) {
+		rc = smb_EIO2(smb_eio_trace_qalleas_overlong,
+			      data_offset, get_bcc(&pSMBr->hdr));
+		goto QAllEAsOut;
+	}
+
+	ea_list_len = le32_to_cpu(ea_response_data->list_len);
+	cifs_dbg(FYI, "%s: ea length: %u\n", __func__, ea_list_len);
+	if (ea_list_len <= 8) {
 		cifs_dbg(FYI, "empty EA list returned from server\n");
 		/* didn't find the named attribute */
 		if (ea_name)
@@ -6307,14 +6319,14 @@ CIFSSMBQAllEAs(const unsigned int xid, struct cifs_tcon *tcon,
 	}
 
 	/* make sure list_len doesn't go past end of SMB */
-	end_of_smb = (char *)pByteArea(&pSMBr->hdr) + get_bcc(&pSMBr->hdr);
-	if ((char *)ea_response_data + list_len > end_of_smb) {
+	if (ea_list_len > end_of_smb - (char *)ea_response_data) {
 		cifs_dbg(FYI, "EA list appears to go beyond SMB\n");
 		rc = smb_EIO2(smb_eio_trace_qalleas_overlong,
-			      (unsigned long)ea_response_data + list_len - (unsigned long)pSMBr,
-			      (unsigned long)end_of_smb - (unsigned long)pSMBr);
+			      ea_list_len,
+			      end_of_smb - (char *)ea_response_data);
 		goto QAllEAsOut;
 	}
+	list_len = ea_list_len;
 
 	/* account for ea list len */
 	list_len -= 4;