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Date:   Mon, 4 Jul 2022 10:54:05 +0800
From:   Baoquan He <bhe@redhat.com>
To:     Jianglei Nie <niejianglei2021@163.com>
Cc:     vgoyal@redhat.com, dyoung@redhat.com, kexec@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] proc/vmcore: fix potential memory leak in vmcore_init()
Message-ID: <YsJWTT71QAfTef5N@MiWiFi-R3L-srv>
References: <20220629165216.2161430-1-niejianglei2021@163.com>
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In-Reply-To: <20220629165216.2161430-1-niejianglei2021@163.com>
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On 06/30/22 at 12:52am, Jianglei Nie wrote:
> elfcorehdr_alloc() allocates a memory chunk for elfcorehdr_addr with
> kzalloc(). If is_vmcore_usable() returns false, elfcorehdr_addr is a
> predefined value. If parse_crash_elf_headers() occurs some error and
> returns a negetive value, the elfcorehdr_addr should be released with
> elfcorehdr_free().
> 
> We can fix by calling elfcorehdr_free() when parse_crash_elf_headers()
> fails.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>  fs/proc/vmcore.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 4eaeb645e759..7e028cd1e59d 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -1568,6 +1568,7 @@ static int __init vmcore_init(void)
>  		return rc;
>  	rc = parse_crash_elf_headers();
>  	if (rc) {
> +		elfcorehdr_free(elfcorehdr_addr);
>  		pr_warn("Kdump: vmcore not initialized\n");
>  		return rc;

Guess it's found by code inspecting since if vmcore_init() failed, kdump
kernel won't do anyting meaningful and reboot, then nobody notice or
care about this leak.

If so, is this better?

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 7e028cd1e59d..ea2f44d77786 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -1568,16 +1568,16 @@ static int __init vmcore_init(void)
 		return rc;
 	rc = parse_crash_elf_headers();
 	if (rc) {
-		elfcorehdr_free(elfcorehdr_addr);
 		pr_warn("Kdump: vmcore not initialized\n");
-		return rc;
+		goto fail;
 	}
-	elfcorehdr_free(elfcorehdr_addr);
 	elfcorehdr_addr = ELFCORE_ADDR_ERR;
 
 	proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &vmcore_proc_ops);
 	if (proc_vmcore)
 		proc_vmcore->size = vmcore_size;
+fail:
+	elfcorehdr_free(elfcorehdr_addr);
 	return 0;
 }
 fs_initcall(vmcore_init);

>  	}
> -- 
> 2.25.1
> 
> 
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