Commit ab02811b authored by Kees Cook's avatar Kees Cook Committed by Pu Lehui
Browse files

bpf, verifier: Fix memory leak in array reallocation for stack state 

mainline inclusion
from mainline-v6.1-rc5
commit 42378a9c
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I932VT
CVE: CVE-2023-52452

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=42378a9ca553



--------------------------------

If an error (NULL) is returned by krealloc(), callers of realloc_array()
were setting their allocation pointers to NULL, but on error krealloc()
does not touch the original allocation. This would result in a memory
resource leak. Instead, free the old allocation on the error handling
path.

The memory leak information is as follows as also reported by Zhengchao:

  unreferenced object 0xffff888019801800 (size 256):
  comm "bpf_repo", pid 6490, jiffies 4294959200 (age 17.170s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000b211474b>] __kmalloc_node_track_caller+0x45/0xc0
    [<0000000086712a0b>] krealloc+0x83/0xd0
    [<00000000139aab02>] realloc_array+0x82/0xe2
    [<00000000b1ca41d1>] grow_stack_state+0xfb/0x186
    [<00000000cd6f36d2>] check_mem_access.cold+0x141/0x1341
    [<0000000081780455>] do_check_common+0x5358/0xb350
    [<0000000015f6b091>] bpf_check.cold+0xc3/0x29d
    [<000000002973c690>] bpf_prog_load+0x13db/0x2240
    [<00000000028d1644>] __sys_bpf+0x1605/0x4ce0
    [<00000000053f29bd>] __x64_sys_bpf+0x75/0xb0
    [<0000000056fedaf5>] do_syscall_64+0x35/0x80
    [<000000002bd58261>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: c69431aa ("bpf: verifier: Improve function state reallocation")
Reported-by: default avatarZhengchao Shao <shaozhengchao@huawei.com>
Reported-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarBill Wendling <morbo@google.com>
Cc: Lorenz Bauer <oss@lmb.io>
Link: https://lore.kernel.org/bpf/20221029025433.2533810-1-keescook@chromium.org


Conflicts:
	kernel/bpf/verifier.c
Signed-off-by: default avatarPu Lehui <pulehui@huawei.com>
parent 876bf652

kernel/bpf/verifier.c

+9 −3
Original line number Diff line number Diff line
@@ -740,16 +740,22 @@ static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t 
static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)

{

	size_t bytes;

	void *new_arr;



	if (!new_n || old_n == new_n)

		goto out;



	if (unlikely(check_mul_overflow(new_n, size, &bytes)))

	if (unlikely(check_mul_overflow(new_n, size, &bytes))) {

		kfree(arr);

		return NULL;

	}



	arr = krealloc(arr, bytes, GFP_KERNEL);

	if (!arr)

	new_arr = krealloc(arr, bytes, GFP_KERNEL);

	if (!new_arr) {

		kfree(arr);

		return NULL;

	}

	arr = new_arr;



	if (new_n > old_n)

		memset(arr + old_n * size, 0, (new_n - old_n) * size);