FAILED: patch "[PATCH] mtd: Avoid boot crash in RedBoot partition table parser" 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 8e2f8020270af7777d49c2e7132260983e4fc566
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026032025-scanning-frying-8ead@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 8e2f8020270af7777d49c2e7132260983e4fc566 Mon Sep 17 00:00:00 2001
From: Finn Thain <fthain@linux-m68k.org>
Date: Mon, 16 Feb 2026 18:01:30 +1100
Subject: [PATCH] mtd: Avoid boot crash in RedBoot partition table parser

Given CONFIG_FORTIFY_SOURCE=y and a recent compiler,
commit 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when
available") produces the warning below and an oops.

    Searching for RedBoot partition table in 50000000.flash at offset 0x7e0000
    ------------[ cut here ]------------
    WARNING: lib/string_helpers.c:1035 at 0xc029e04c, CPU#0: swapper/0/1
    memcmp: detected buffer overflow: 15 byte read of buffer size 14
    Modules linked in:
    CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.19.0 #1 NONE

As Kees said, "'names' is pointing to the final 'namelen' many bytes
of the allocation ... 'namelen' could be basically any length at all.
This fortify warning looks legit to me -- this code used to be reading
beyond the end of the allocation."

Since the size of the dynamic allocation is calculated with strlen()
we can use strcmp() instead of memcmp() and remain within bounds.

Cc: Kees Cook <kees@kernel.org>
Cc: stable@vger.kernel.org
Cc: linux-hardening@vger.kernel.org
Link: https://lore.kernel.org/all/202602151911.AD092DFFCD@keescook/
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Suggested-by: Kees Cook <kees@kernel.org>
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

diff --git a/drivers/mtd/parsers/redboot.c b/drivers/mtd/parsers/redboot.c
index 558905160ddb..bf162c44eafe 100644
--- a/drivers/mtd/parsers/redboot.c
+++ b/drivers/mtd/parsers/redboot.c
@@ -270,9 +270,9 @@ nogood:
 
 		strcpy(names, fl->img->name);
 #ifdef CONFIG_MTD_REDBOOT_PARTS_READONLY
-		if (!memcmp(names, "RedBoot", 8) ||
-		    !memcmp(names, "RedBoot config", 15) ||
-		    !memcmp(names, "FIS directory", 14)) {
+		if (!strcmp(names, "RedBoot") ||
+		    !strcmp(names, "RedBoot config") ||
+		    !strcmp(names, "FIS directory")) {
 			parts[i].mask_flags = MTD_WRITEABLE;
 		}
 #endif