From: Song Liu <song@kernel.org>
Date: Thu, 17 Feb 2022 10:30:01 -0800
Subject: bpf: bpf_prog_pack: Set proper size before freeing ro_header
Patch-mainline: v5.18-rc1
Git-commit: d24d2a2b0a81dd5e9bb99aeb4559ec9734e1416f
References: jsc#PED-1377

bpf_prog_pack_free() uses header->size to decide whether the header
should be freed with module_memfree() or the bpf_prog_pack logic.
However, in kvmalloc() failure path of bpf_jit_binary_pack_alloc(),
header->size is not set yet. As a result, bpf_prog_pack_free() may treat
a slice of a pack as a standalone kvmalloc'd header and call
module_memfree() on the whole pack. This in turn causes use-after-free by
other users of the pack.

Fix this by setting ro_header->size before freeing ro_header.

Fixes: 33c9805860e5 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
Reported-by: syzbot+2f649ec6d2eea1495a8f@syzkaller.appspotmail.com
Reported-by: syzbot+ecb1e7e51c52f68f7481@syzkaller.appspotmail.com
Reported-by: syzbot+87f65c75f4a72db05445@syzkaller.appspotmail.com
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220217183001.1876034-1-song@kernel.org
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 kernel/bpf/core.c |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1069,6 +1069,7 @@ bpf_jit_binary_pack_alloc(unsigned int p
 
 	*rw_header = kvmalloc(size, GFP_KERNEL);
 	if (!*rw_header) {
+		bpf_arch_text_copy(&ro_header->size, &size, sizeof(size));
 		bpf_prog_pack_free(ro_header);
 		bpf_jit_uncharge_modmem(size);
 		return NULL;