Re: [PATCH] powerpc/bpf: fix write protecting JIT code

Hari Bathini wrote:

Running program with bpf-to-bpf function calls results in data access exception (0x300) with the below call trace:

[c000000000113f28] bpf_int_jit_compile+0x238/0x750 (unreliable)
[c00000000037d2f8] bpf_check+0x2008/0x2710
[c000000000360050] bpf_prog_load+0xb00/0x13a0
[c000000000361d94] __sys_bpf+0x6f4/0x27c0
[c000000000363f0c] sys_bpf+0x2c/0x40
[c000000000032434] system_call_exception+0x164/0x330
[c00000000000c1e8] 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.

Cc: stable@vger.kernel.org Fixes: 62e3d4210ac9 ("powerpc/bpf: Write protect JIT code") Signed-off-by: Hari Bathini hbathini@linux.ibm.com

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arch/powerpc/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

Thanks for the fix!

Reviewed-by: Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com