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

PATCH New [email protected] 2 participants 2 messages Nov 4 – Nov 6

Subsystems (2)

Stable branch SMB client (CIFS)

lore

Share & tools

lore

[email protected]

author maintainer

2026-11-04 18:35 UTC #0 lore raw

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 <[email protected]>.

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 '<[email protected]>' --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 <[email protected]>
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 [email protected]

Signed-off-by Ratnaker Gautam <[email protected]>

Signed-off-by Paulo Alcantara <[email protected]>

fs/smb/client/cifssmb.c +19 -7

index 9ffc94ac2069..2936b38de98f 100644
@@ -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;

Sasha Levin

maintainer

2026-11-06 01:54 UTC #1 lore raw

PATCH 1/1 smb: client: validate SMB1 EA list bounds before parsing

From: Ratnaker Gautam <[email protected]>

[ Upstream commit ddc7a7e1eeb116ccaf010a6f1fb6ab927f3f888d ]

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 [email protected]

Signed-off-by Ratnaker Gautam <[email protected]>

Signed-off-by Paulo Alcantara <[email protected]>

[ sashal: replaced smb_EIO2() calls with direct -EIO assignments ]

Signed-off-by Sasha Levin <[email protected]>

---
 fs/cifs/cifssmb.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

fs/cifs/cifssmb.c +16 -5

index 67ff1669cab2a..6926291316809 100644
@@ -6201,9 +6201,11 @@ 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;

@@ -6280,9 +6282,18 @@ 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 = -EIO;
+		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)

@@ -6291,12 +6302,12 @@ 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 = -EIO;
 		goto QAllEAsOut;
 	}
+	list_len = ea_list_len;
 
 	/* account for ea list len */
 	list_len -= 4;

Signature · 1 line

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