On Tue, Oct 30, 2018 at 11:10:51AM -0300, Ard Biesheuvel wrote:
> On 30 October 2018 at 08:49, Ard Biesheuvel <ard.biesheu...@linaro.org> wrote:
> >> On 30 Oct 2018, at 08:38, Anders Roxell <anders.rox...@linaro.org> wrote:
> >>
> >> Commit 1404d6f13e47 ("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 63fef14fc98a ("kprobes/x86: Make insn buffer always ROX and use
> >> text_poke()").
> >>
> >> Cc: Laura Abbott <labb...@redhat.com>
> >> Cc: Catalin Marinas <catalin.mari...@arm.com>
> >> Co-developed-by: Arnd Bergmann <a...@arndb.de>
> >> Co-developed-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
> >> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> >> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
> >
> > Please remove these SOBs, Arnd and I provided input to this patch
> > but you are the one sending it (sob does not assert authorship or
> > anything like that, it just asserts that the code in the patch was
> > made available under a compatible license)
>
> As Anders points out in a private communication, the Documentation/
> explicitly requires signoffs for Co-developed-by credits. Perhaps we
> should enhance that document to clarify that that does not mean you
> can simply add signoffs on someone else's behalf.
I think I'll rename co-developed-by with suggested-by to keep things
simpler. Are you ok with this (or are you providing an explicit
signed-off-by)?
--
Catalin
