2018-12-27 18:15:41

by Dave Young

Subject: [PATCH] x86/kexec: fix a kexec_file_load failure

The code cleanup mentioned in Fixes tag changed the behavior of
kexec_locate_mem_hole. The kexec_locate_mem_hole will try to
allocate free memory only when kbuf.mem is initialized as zero.

But in x86 kexec_file_load implementation there are a few places
the kbuf.mem is reused like below:
/* kbuf initialized, kbuf.mem = 0 */
...
kexec_add_buffer()
...
kexec_add_buffer()

The second kexec_add_buffer will reuse previous kbuf but not
reinitialize the kbuf.mem.

Thus kexec_file_load failed because the sanity check failed.

So explictily reset mem = 0 to fix the issue.

Fixes: b6664ba42f14 ("s390, kexec_file: drop arch_kexec_mem_walk()")
Signed-off-by: Dave Young <[email protected]>
Cc: <[email protected]>
---
arch/x86/kernel/crash.c | 1 +
arch/x86/kernel/kexec-bzimage64.c | 2 ++
2 files changed, 3 insertions(+)

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index f631a3f15587..37147509d2c8 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -469,6 +469,7 @@ int crash_load_segments(struct kimage *image)

kbuf.memsz = kbuf.bufsz;
kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
+ kbuf.mem = 0;
ret = kexec_add_buffer(&kbuf);
if (ret) {
vfree((void *)image->arch.elf_headers);
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 278cd07228dd..558204bdf412 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -434,6 +434,7 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
kbuf.memsz = PAGE_ALIGN(header->init_size);
kbuf.buf_align = header->kernel_alignment;
kbuf.buf_min = MIN_KERNEL_LOAD_ADDR;
+ kbuf.mem = 0;
ret = kexec_add_buffer(&kbuf);
if (ret)
goto out_free_params;
@@ -448,6 +449,7 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
kbuf.bufsz = kbuf.memsz = initrd_len;
kbuf.buf_align = PAGE_SIZE;
kbuf.buf_min = MIN_INITRD_LOAD_ADDR;
+ kbuf.mem = 0;
ret = kexec_add_buffer(&kbuf);
if (ret)
goto out_free_params;
--
2.17.0

2018-12-28 13:32:50

by Dave Young

Subject: Re: [PATCH] x86/kexec: fix a kexec_file_load failure

On 12/27/18 at 01:06pm, Dave Young wrote:
> The code cleanup mentioned in Fixes tag changed the behavior of
> kexec_locate_mem_hole. The kexec_locate_mem_hole will try to
> allocate free memory only when kbuf.mem is initialized as zero.
>
> But in x86 kexec_file_load implementation there are a few places
> the kbuf.mem is reused like below:
> /* kbuf initialized, kbuf.mem = 0 */
> ...
> kexec_add_buffer()
> ...
> kexec_add_buffer()
>
> The second kexec_add_buffer will reuse previous kbuf but not
> reinitialize the kbuf.mem.
>
> Thus kexec_file_load failed because the sanity check failed.
>
> So explictily reset mem = 0 to fix the issue.
>
> Fixes: b6664ba42f14 ("s390, kexec_file: drop arch_kexec_mem_walk()")
> Signed-off-by: Dave Young <[email protected]>
> Cc: <[email protected]>
> ---
> arch/x86/kernel/crash.c | 1 +
> arch/x86/kernel/kexec-bzimage64.c | 2 ++
> 2 files changed, 3 insertions(+)
>
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index f631a3f15587..37147509d2c8 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -469,6 +469,7 @@ int crash_load_segments(struct kimage *image)
>
> kbuf.memsz = kbuf.bufsz;
> kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
> + kbuf.mem = 0;

Self NAK, will resend with KEXEC_BUF_MEM_UNKNOWN instead of "0"

> ret = kexec_add_buffer(&kbuf);
> if (ret) {
> vfree((void *)image->arch.elf_headers);
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 278cd07228dd..558204bdf412 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -434,6 +434,7 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
> kbuf.memsz = PAGE_ALIGN(header->init_size);
> kbuf.buf_align = header->kernel_alignment;
> kbuf.buf_min = MIN_KERNEL_LOAD_ADDR;
> + kbuf.mem = 0;
> ret = kexec_add_buffer(&kbuf);
> if (ret)
> goto out_free_params;
> @@ -448,6 +449,7 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
> kbuf.bufsz = kbuf.memsz = initrd_len;
> kbuf.buf_align = PAGE_SIZE;
> kbuf.buf_min = MIN_INITRD_LOAD_ADDR;
> + kbuf.mem = 0;
> ret = kexec_add_buffer(&kbuf);
> if (ret)
> goto out_free_params;
> --
> 2.17.0
>