File 0020-commands-menuentry-Fix-quoting-in-setparam... of Package grub2.26833

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File 0020-commands-menuentry-Fix-quoting-in-setparams_prefix.patch of Package grub2.26833

From d4cfde41ebbe3f9e024119c6d18c4794a107eec9 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Fri, 22 Jan 2021 17:10:48 +1100
Subject: [PATCH 20/41] commands/menuentry: Fix quoting in setparams_prefix()

Commit 9acdcbf32542 (use single quotes in menuentry setparams command)
says that expressing a quoted single quote will require 3 characters. It
actually requires (and always did require!) 4 characters:

str: a'b => a'\''b
  len:  3  => 6 (2 for the letters + 4 for the quote)

This leads to not allocating enough memory and thus out of bounds writes
that have been observed to cause heap corruption.

Allocate 4 bytes for each single quote.

Commit 22e7dbb2bb81 (Fix quoting in legacy parser.) does the same
quoting, but it adds 3 as extra overhead on top of the single byte that
the quote already needs. So it's correct.

Fixes: CVE-2021-20233
Fixes: 9acdcbf32542 (use single quotes in menuentry setparams command)

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 grub-core/commands/menuentry.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/grub-core/commands/menuentry.c b/grub-core/commands/menuentry.c
index 948d7711a..1d4a7e25c 100644
--- a/grub-core/commands/menuentry.c
+++ b/grub-core/commands/menuentry.c
@@ -233,7 +233,7 @@ setparams_prefix (int argc, char **args)
       len += 3; /* 3 = 1 space + 2 quotes */
       p = args[i];
       while (*p)
-	len += (*p++ == '\'' ? 3 : 1);
+	len += (*p++ == '\'' ? 4 : 1);
     }
 
   result = grub_malloc (len + 2);
-- 
2.26.2

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File 0020-commands-menuentry-Fix-quoting-in-setparams_prefix.patch of Package grub2.26833

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