[PATCH v3] proc/vmcore: fix potential memory leak in vmcore_init()

[PATCH v3] proc/vmcore: fix potential memory leak in vmcore_init()

[Jianglei Nie]

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 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 4eaeb645e759..125efe63f281 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -1569,7 +1569,7 @@ static int __init vmcore_init(void)
 	rc = parse_crash_elf_headers();
 	if (rc) {
 		pr_warn("Kdump: vmcore not initialized\n");
-		return rc;
+		goto fail;
 	}
 	elfcorehdr_free(elfcorehdr_addr);
 	elfcorehdr_addr = ELFCORE_ADDR_ERR;
@@ -1578,6 +1578,9 @@ static int __init vmcore_init(void)
 	if (proc_vmcore)
 		proc_vmcore->size = vmcore_size;
 	return 0;
+fail:
+	elfcorehdr_free(elfcorehdr_addr);
+	return rc;
 }
 fs_initcall(vmcore_init);
 
-- 
2.25.1

Re: [PATCH v3] proc/vmcore: fix potential memory leak in vmcore_init()

[Baoquan He]

On 07/11/22 at 03:34pm, 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 | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 4eaeb645e759..125efe63f281 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -1569,7 +1569,7 @@ static int __init vmcore_init(void)
>  	rc = parse_crash_elf_headers();
>  	if (rc) {
>  		pr_warn("Kdump: vmcore not initialized\n");
> -		return rc;
> +		goto fail;

Sigh. Why don't you copy my suggested code directly?

>  	}
>  	elfcorehdr_free(elfcorehdr_addr);

Remove above line.

>  	elfcorehdr_addr = ELFCORE_ADDR_ERR;
> @@ -1578,6 +1578,9 @@ static int __init vmcore_init(void)
>  	if (proc_vmcore)
>  		proc_vmcore->size = vmcore_size;
>  	return 0;

Remove above line too.

> +fail:
> +	elfcorehdr_free(elfcorehdr_addr);
> +	return rc;
>  }
>  fs_initcall(vmcore_init);
>  
> -- 
> 2.25.1
> 

Re: [PATCH v3] proc/vmcore: fix potential memory leak in vmcore_init()

[Matthew Wilcox]

On Mon, Jul 11, 2022 at 03:49:51PM +0800, Baoquan He wrote:
> On 07/11/22 at 03:34pm, 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 | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> > index 4eaeb645e759..125efe63f281 100644
> > --- a/fs/proc/vmcore.c
> > +++ b/fs/proc/vmcore.c
> > @@ -1569,7 +1569,7 @@ static int __init vmcore_init(void)
> >  	rc = parse_crash_elf_headers();
> >  	if (rc) {
> >  		pr_warn("Kdump: vmcore not initialized\n");
> > -		return rc;
> > +		goto fail;
> 
> Sigh. Why don't you copy my suggested code directly?

I think at this point, you should just submit your own patch
and credit this person with Reported-by:

Re: [PATCH v3] proc/vmcore: fix potential memory leak in vmcore_init()

[Baoquan He]

On 07/11/22 at 01:18pm, Matthew Wilcox wrote:
> On Mon, Jul 11, 2022 at 03:49:51PM +0800, Baoquan He wrote:
> > On 07/11/22 at 03:34pm, 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 | 5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> > > index 4eaeb645e759..125efe63f281 100644
> > > --- a/fs/proc/vmcore.c
> > > +++ b/fs/proc/vmcore.c
> > > @@ -1569,7 +1569,7 @@ static int __init vmcore_init(void)
> > >  	rc = parse_crash_elf_headers();
> > >  	if (rc) {
> > >  		pr_warn("Kdump: vmcore not initialized\n");
> > > -		return rc;
> > > +		goto fail;
> > 
> > Sigh. Why don't you copy my suggested code directly?
> 
> I think at this point, you should just submit your own patch
> and credit this person with Reported-by:

Thanks for telling. I will consider doing this in the future.