• Bug#1085178: Re: Bug#1085178: linux-signed-amd64: Some BPF fentry hooks

    From Salvatore Bonaccorso@21:1/5 to Martin Kelly on Mon Apr 21 14:20:01 2025
    XPost: linux.debian.kernel

    Control: tags -1 + fixed-upstream

    On Fri, Feb 21, 2025 at 09:43:34PM +0000, Martin Kelly wrote:
    On Fri, 2025-02-21 at 21:03 +0100, Salvatore Bonaccorso wrote:


    Essentially this has to do with ftrace and weak functions.

    As I understand this is still an issue in 6.12.15-1.


    That's correct; 6.12.15 should still be impacted, as long as CONFIG_X86_KERNEL_IBT is set. CONFIG_X86_KERNEL_IBT changes the
    function prologue in a way that causes this issue when combined with an certain fentry bug.

    I confirmed this issue is fixed with this patch series: https://lore.kernel.org/bpf/20250218195918.255228630@goodmis.org/
    Since that fixes the underlying fentry bug.

    I would guess that series will merge into 6.15, but we'll have to see.

    AFAICS, this has been merged for 6.15-rc1 with https://git.kernel.org/linus/dd161f74f8198c62f9bcf893f72c64bbb0d68b25

    Not sure they will be backported down to 6.12.y.

    Regards,
    Salvatore

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