Commit 1f97c03f authored by Hou Tao's avatar Hou Tao Committed by Andrii Nakryiko
Browse files

bpf: Preserve param->string when parsing mount options 



In bpf_parse_param(), keep the value of param->string intact so it can
be freed later. Otherwise, the kmalloc area pointed to by param->string
will be leaked as shown below:

unreferenced object 0xffff888118c46d20 (size 8):
  comm "new_name", pid 12109, jiffies 4295580214
  hex dump (first 8 bytes):
    61 6e 79 00 38 c9 5c 7e                          any.8.\~
  backtrace (crc e1b7f876):
    [<00000000c6848ac7>] kmemleak_alloc+0x4b/0x80
    [<00000000de9f7d00>] __kmalloc_node_track_caller_noprof+0x36e/0x4a0
    [<000000003e29b886>] memdup_user+0x32/0xa0
    [<0000000007248326>] strndup_user+0x46/0x60
    [<0000000035b3dd29>] __x64_sys_fsconfig+0x368/0x3d0
    [<0000000018657927>] x64_sys_call+0xff/0x9f0
    [<00000000c0cabc95>] do_syscall_64+0x3b/0xc0
    [<000000002f331597>] entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fixes: 6c1752e0 ("bpf: Support symbolic BPF FS delegation mount options")
Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20241022130133.3798232-1-houtao@huaweicloud.com
parent a552e2ef

kernel/bpf/inode.c

+3 −2
Original line number Diff line number Diff line
@@ -880,7 +880,7 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) 
		const struct btf_type *enum_t;

		const char *enum_pfx;

		u64 *delegate_msk, msk = 0;

		char *p;

		char *p, *str;

		int val;



		/* ignore errors, fallback to hex */
@@ -911,7 +911,8 @@ static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) 
			return -EINVAL;

		}



		while ((p = strsep(&param->string, ":"))) {

		str = param->string;

		while ((p = strsep(&str, ":"))) {

			if (strcmp(p, "any") == 0) {

				msk |= ~0ULL;

			} else if (find_btf_enum_const(info.btf, enum_t, enum_pfx, p, &val)) {