This is a note to let you know that I've just added the patch titled
powerpc/bpf: Fix write protecting JIT code
to the 5.14-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:
powerpc-bpf-fix-write-protecting-jit-code.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 44a8214de96bafb5210e43bfa2c97c19bf75af3d Mon Sep 17 00:00:00 2001
From: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Date: Mon, 25 Oct 2021 11:26:49 +0530
Subject: powerpc/bpf: Fix write protecting JIT code
From: Hari Bathini <hbathini@xxxxxxxxxxxxx>
commit 44a8214de96bafb5210e43bfa2c97c19bf75af3d upstream.
Running program with bpf-to-bpf function calls results in data access
exception (0x300) with the below call trace:
bpf_int_jit_compile+0x238/0x750 (unreliable)
bpf_check+0x2008/0x2710
bpf_prog_load+0xb00/0x13a0
__sys_bpf+0x6f4/0x27c0
sys_bpf+0x2c/0x40
system_call_exception+0x164/0x330
system_call_vectored_common+0xe8/0x278
as bpf_int_jit_compile() tries writing to write protected JIT code
location during the extra pass.
Fix it by holding off write protection of JIT code until the extra
pass, where branch target addresses fixup happens.
Fixes: 62e3d4210ac9 ("powerpc/bpf: Write protect JIT code")
Cc: stable@xxxxxxxxxxxxxxx # v5.14+
Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Reviewed-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211025055649.114728-1-hbathini@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/net/bpf_jit_comp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -241,8 +241,8 @@ skip_codegen_passes:
fp->jited_len = alloclen;
bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + (bpf_hdr->pages * PAGE_SIZE));
- bpf_jit_binary_lock_ro(bpf_hdr);
if (!fp->is_func || extra_pass) {
+ bpf_jit_binary_lock_ro(bpf_hdr);
bpf_prog_fill_jited_linfo(fp, addrs);
out_addrs:
kfree(addrs);
Patches currently in stable-queue which might be from hbathini@xxxxxxxxxxxxx are
queue-5.14/powerpc-bpf-fix-write-protecting-jit-code.patch
