Patch "bpf: Fill new bpf_prog_pack with illegal instructions" has been added to the 5.18-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    bpf: Fill new bpf_prog_pack with illegal instructions

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bpf-fill-new-bpf_prog_pack-with-illegal-instructions.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From d88bb5eed04ce50cc20e7f9282977841728be798 Mon Sep 17 00:00:00 2001
From: Song Liu <song@xxxxxxxxxx>
Date: Fri, 20 May 2022 16:57:51 -0700
Subject: bpf: Fill new bpf_prog_pack with illegal instructions

From: Song Liu <song@xxxxxxxxxx>

commit d88bb5eed04ce50cc20e7f9282977841728be798 upstream.

bpf_prog_pack enables sharing huge pages among multiple BPF programs.
These pages are marked as executable before the JIT engine fill it with
BPF programs. To make these pages safe, fill the hole bpf_prog_pack with
illegal instructions before making it executable.

Fixes: 57631054fae6 ("bpf: Introduce bpf_prog_pack allocator")
Fixes: 33c9805860e5 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220520235758.1858153-2-song@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/bpf/core.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -873,7 +873,7 @@ static size_t select_bpf_prog_pack_size(
 	return size;
 }
 
-static struct bpf_prog_pack *alloc_new_pack(void)
+static struct bpf_prog_pack *alloc_new_pack(bpf_jit_fill_hole_t bpf_fill_ill_insns)
 {
 	struct bpf_prog_pack *pack;
 
@@ -886,6 +886,7 @@ static struct bpf_prog_pack *alloc_new_p
 		kfree(pack);
 		return NULL;
 	}
+	bpf_fill_ill_insns(pack->ptr, bpf_prog_pack_size);
 	bitmap_zero(pack->bitmap, bpf_prog_pack_size / BPF_PROG_CHUNK_SIZE);
 	list_add_tail(&pack->list, &pack_list);
 
@@ -895,7 +896,7 @@ static struct bpf_prog_pack *alloc_new_p
 	return pack;
 }
 
-static void *bpf_prog_pack_alloc(u32 size)
+static void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns)
 {
 	unsigned int nbits = BPF_PROG_SIZE_TO_NBITS(size);
 	struct bpf_prog_pack *pack;
@@ -910,6 +911,7 @@ static void *bpf_prog_pack_alloc(u32 siz
 		size = round_up(size, PAGE_SIZE);
 		ptr = module_alloc(size);
 		if (ptr) {
+			bpf_fill_ill_insns(ptr, size);
 			set_vm_flush_reset_perms(ptr);
 			set_memory_ro((unsigned long)ptr, size / PAGE_SIZE);
 			set_memory_x((unsigned long)ptr, size / PAGE_SIZE);
@@ -923,7 +925,7 @@ static void *bpf_prog_pack_alloc(u32 siz
 			goto found_free_area;
 	}
 
-	pack = alloc_new_pack();
+	pack = alloc_new_pack(bpf_fill_ill_insns);
 	if (!pack)
 		goto out;
 
@@ -1102,7 +1104,7 @@ bpf_jit_binary_pack_alloc(unsigned int p
 
 	if (bpf_jit_charge_modmem(size))
 		return NULL;
-	ro_header = bpf_prog_pack_alloc(size);
+	ro_header = bpf_prog_pack_alloc(size, bpf_fill_ill_insns);
 	if (!ro_header) {
 		bpf_jit_uncharge_modmem(size);
 		return NULL;


Patches currently in stable-queue which might be from song@xxxxxxxxxx are

queue-5.18/raid5-introduce-md_broken.patch
queue-5.18/bpf-fill-new-bpf_prog_pack-with-illegal-instructions.patch