Patch "bpf: Fix atomic probe zero-extension" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    bpf: Fix atomic probe zero-extension

to the 6.10-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-fix-atomic-probe-zero-extension.patch
and it can be found in the queue-6.10 subdirectory.

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



commit 6db4b0df87bf946c5bd3a52f89e8b96b6011a101
Author: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Date:   Tue Jul 2 01:40:19 2024 +0200

    bpf: Fix atomic probe zero-extension
    
    [ Upstream commit df34ec9db6f521118895f22795da49f2ec01f8cf ]
    
    Zero-extending results of atomic probe operations fails with:
    
        verifier bug. zext_dst is set, but no reg is defined
    
    The problem is that insn_def_regno() handles BPF_ATOMICs, but not
    BPF_PROBE_ATOMICs. Fix by adding the missing condition.
    
    Fixes: d503a04f8bc0 ("bpf: Add support for certain atomics in bpf_arena to x86 JIT")
    Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
    Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
    Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/bpf/20240701234304.14336-2-iii@xxxxxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 214a9fa8c6fb7..e1e08e62a2f2f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3215,7 +3215,8 @@ static int insn_def_regno(const struct bpf_insn *insn)
 	case BPF_ST:
 		return -1;
 	case BPF_STX:
-		if (BPF_MODE(insn->code) == BPF_ATOMIC &&
+		if ((BPF_MODE(insn->code) == BPF_ATOMIC ||
+		     BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) &&
 		    (insn->imm & BPF_FETCH)) {
 			if (insn->imm == BPF_CMPXCHG)
 				return BPF_REG_0;