2022-06-29 17:52:40

by Jianglei Nie

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

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 <[email protected]>
---
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;
}
--
2.25.1

2022-07-04 03:28:54

by Baoquan He

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

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 <[email protected]>
> ---
> 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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