• Anders Roxell's avatar
    arm64: kprobe: make page to RO mode when allocate it · 96686689
    Anders Roxell authored
    Commit 1404d6f1 ("arm64: dump: Add checking for writable and exectuable pages")
    has successfully identified code that leaves a page with W+X
    permissions.
    
    [    3.245140] arm64/mm: Found insecure W+X mapping at address (____ptrval____)/0xffff000000d90000
    [    3.245771] WARNING: CPU: 0 PID: 1 at ../arch/arm64/mm/dump.c:232 note_page+0x410/0x420
    [    3.246141] Modules linked in:
    [    3.246653] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc5-next-20180928-00001-ge70ae259b853-dirty #62
    [    3.247008] Hardware name: linux,dummy-virt (DT)
    [    3.247347] pstate: 80000005 (Nzcv daif -PAN -UAO)
    [    3.247623] pc : note_page+0x410/0x420
    [    3.247898] lr : note_page+0x410/0x420
    [    3.248071] sp : ffff00000804bcd0
    [    3.248254] x29: ffff00000804bcd0 x28: ffff000009274000
    [    3.248578] x27: ffff00000921a000 x26: ffff80007dfff000
    [    3.248845] x25: ffff0000093f5000 x24: ffff000009526f6a
    [    3.249109] x23: 0000000000000004 x22: ffff000000d91000
    [    3.249396] x21: ffff000000d90000 x20: 0000000000000000
    [    3.249661] x19: ffff00000804bde8 x18: 0000000000000400
    [    3.249924] x17: 0000000000000000 x16: 0000000000000000
    [    3.250271] x15: ffffffffffffffff x14: 295f5f5f5f6c6176
    [    3.250594] x13: 7274705f5f5f5f28 x12: 2073736572646461
    [    3.250941] x11: 20746120676e6970 x10: 70616d20582b5720
    [    3.251252] x9 : 6572756365736e69 x8 : 3039643030303030
    [    3.251519] x7 : 306666666678302f x6 : ffff0000095467b2
    [    3.251802] x5 : 0000000000000000 x4 : 0000000000000000
    [    3.252060] x3 : 0000000000000000 x2 : ffffffffffffffff
    [    3.252323] x1 : 4d151327adc50b00 x0 : 0000000000000000
    [    3.252664] Call trace:
    [    3.252953]  note_page+0x410/0x420
    [    3.253186]  walk_pgd+0x12c/0x238
    [    3.253417]  ptdump_check_wx+0x68/0xf8
    [    3.253637]  mark_rodata_ro+0x68/0x98
    [    3.253847]  kernel_init+0x38/0x160
    [    3.254103]  ret_from_fork+0x10/0x18
    
    kprobes allocates a writable executable page with module_alloc() in
    order to store executable code.
    Reworked to that when allocate a page it sets mode RO. Inspired by
    commit 63fef14f ("kprobes/x86: Make insn buffer always ROX and use text_poke()").
    Suggested-by: default avatarArnd Bergmann <arnd@arndb.de>
    Suggested-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
    Acked-by: default avatarWill Deacon <will.deacon@arm.com>
    Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
    Reviewed-by: default avatarLaura Abbott <labbott@redhat.com>
    Signed-off-by: default avatarAnders Roxell <anders.roxell@linaro.org>
    [catalin.marinas@arm.com: removed unnecessary casts]
    Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
    96686689
kprobes.c 15.1 KB