From: Baoquan He bhe@redhat.com

commit b3e34a47f98974d0844444c5121aaff123004e57 upstream.

This is reported by kmemleak detector:

unreferenced object 0xffffc900002a9000 (size 4096): comm "kexec", pid 14950, jiffies 4295110793 (age 373.951s) hex dump (first 32 bytes): 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 .ELF............ 04 00 3e 00 01 00 00 00 00 00 00 00 00 00 00 00 ..>............. backtrace: [<0000000016a8ef9f>] __vmalloc_node_range+0x101/0x170 [<000000002b66b6c0>] __vmalloc_node+0xb4/0x160 [<00000000ad40107d>] crash_prepare_elf64_headers+0x8e/0xcd0 [<0000000019afff23>] crash_load_segments+0x260/0x470 [<0000000019ebe95c>] bzImage64_load+0x814/0xad0 [<0000000093e16b05>] arch_kexec_kernel_image_load+0x1be/0x2a0 [<000000009ef2fc88>] kimage_file_alloc_init+0x2ec/0x5a0 [<0000000038f5a97a>] __do_sys_kexec_file_load+0x28d/0x530 [<0000000087c19992>] do_syscall_64+0x3b/0x90 [<0000000066e063a4>] entry_SYSCALL_64_after_hwframe+0x44/0xae

In crash_prepare_elf64_headers(), a buffer is allocated via vmalloc() to store elf headers. While it's not freed back to system correctly when kdump kernel is reloaded or unloaded. Then memory leak is caused. Fix it by introducing x86 specific function arch_kimage_file_post_load_cleanup(), and freeing the buffer there.

And also remove the incorrect elf header buffer freeing code. Before calling arch specific kexec_file loading function, the image instance has been initialized. So 'image->elf_headers' must be NULL. It doesn't make sense to free the elf header buffer in the place.

Three different people have reported three bugs about the memory leak on x86_64 inside Redhat.

Link: https://lkml.kernel.org/r/20220223113225.63106-2-bhe@redhat.com Signed-off-by: Baoquan He bhe@redhat.com Acked-by: Dave Young dyoung@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [Conflict due to 179350f00e06 ("x86: Use ELF fields defined in 'struct kimage'") not in the tree] Signed-off-by: Abdelkareem Abdelsaamad kareemem@amazon.com --- arch/x86/kernel/machine_kexec_64.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index a29a44a98e5b..19f6aafd595a 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -402,9 +402,6 @@ void machine_kexec(struct kimage *image) #ifdef CONFIG_KEXEC_FILE void *arch_kexec_kernel_image_load(struct kimage *image) { - vfree(image->arch.elf_headers); - image->arch.elf_headers = NULL; - if (!image->fops || !image->fops->load) return ERR_PTR(-ENOEXEC);

@@ -540,6 +537,15 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi, (int)ELF64_R_TYPE(rel[i].r_info), value); return -ENOEXEC; } + +int arch_kimage_file_post_load_cleanup(struct kimage *image) +{ + vfree(image->arch.elf_headers); + image->arch.elf_headers = NULL; + image->arch.elf_headers_sz = 0; + + return kexec_image_post_load_cleanup_default(image); +} #endif /* CONFIG_KEXEC_FILE */

static int