linux-kernel - [PATCH] x86/kaslr: Fix potential dereference of NULL pointer.

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Date:   Mon, 17 Apr 2023 23:53:08 -0700
From:   Daniil Dulov <d.dulov@...ddin.ru>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     Daniil Dulov <d.dulov@...ddin.ru>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Baoquan He <bhe@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        <linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>
Subject: [PATCH] x86/kaslr: Fix potential dereference of NULL pointer.

Pointer val can have NULL value. Then its value is assigned to the pointer p.
p is dereferenced by calling strcmp().

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 4cdba14f84c9 ("x86/KASLR: Handle the memory limit specified by the 'memmap=' and 'mem=' boot options")
Signed-off-by: Daniil Dulov <d.dulov@...ddin.ru>
---
 arch/x86/boot/compressed/kaslr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index b92fffbe761f..51b3925d4d2d 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -291,7 +291,7 @@ static void handle_mem_options(void)
 		} else if (!strcmp(param, "mem")) {
 			char *p = val;
 
-			if (!strcmp(p, "nopentium"))
+			if (!p || !strcmp(p, "nopentium"))
 				continue;
 			mem_size = memparse(p, &p);
 			if (mem_size == 0)
-- 
2.25.1