The patch titled Subject: x86/kexec: fix memory leak of elf header buffer has been added to the -mm mm-hotfixes-unstable branch. Its filename is x86-kexec-fix-memory-leak-of-elf-header-buffer.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Baoquan He bhe@redhat.com Subject: x86/kexec: fix memory leak of elf header buffer Date: Wed, 23 Feb 2022 19:32:24 +0800

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 ---

arch/x86/kernel/machine_kexec_64.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/machine_kexec_64.c~x86-kexec-fix-memory-leak-of-elf-header-buffer +++ a/arch/x86/kernel/machine_kexec_64.c @@ -376,9 +376,6 @@ void machine_kexec(struct kimage *image) #ifdef CONFIG_KEXEC_FILE void *arch_kexec_kernel_image_load(struct kimage *image) { - vfree(image->elf_headers); - image->elf_headers = NULL; - if (!image->fops || !image->fops->load) return ERR_PTR(-ENOEXEC);

@@ -514,6 +511,15 @@ overflow: (int)ELF64_R_TYPE(rel[i].r_info), value); return -ENOEXEC; } + +int arch_kimage_file_post_load_cleanup(struct kimage *image) +{ + vfree(image->elf_headers); + image->elf_headers = NULL; + image->elf_headers_sz = 0; + + return kexec_image_post_load_cleanup_default(image); +} #endif /* CONFIG_KEXEC_FILE */

static int _

Patches currently in -mm which might be from bhe@redhat.com are

x86-kexec-fix-memory-leak-of-elf-header-buffer.patch