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author | Marc Zyngier <marc.zyngier@arm.com> | 2015-02-24 16:30:21 +0000 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-02-26 18:34:27 +0000 |
commit | f6242cac10427c546271050b31c891a078e490cd (patch) | |
tree | 71ac3ae50d0938c65f8651b26485386310931f67 | |
parent | 0eee0fbd41c7b57d01136df2519c92ec1506e333 (diff) | |
download | linux-f6242cac10427c546271050b31c891a078e490cd.tar.bz2 |
arm64: Fix text patching logic when using fixmap
Patch 2f896d586610 ("arm64: use fixmap for text patching") changed
the way we patch the kernel text, using a fixmap when the kernel or
modules are flagged as read only.
Unfortunately, a flaw in the logic makes it fall over when patching
modules without CONFIG_DEBUG_SET_MODULE_RONX enabled:
[...]
[ 32.032636] Call trace:
[ 32.032716] [<fffffe00003da0dc>] __copy_to_user+0x2c/0x60
[ 32.032837] [<fffffe0000099f08>] __aarch64_insn_write+0x94/0xf8
[ 32.033027] [<fffffe000009a0a0>] aarch64_insn_patch_text_nosync+0x18/0x58
[ 32.033200] [<fffffe000009c3ec>] ftrace_modify_code+0x58/0x84
[ 32.033363] [<fffffe000009c4e4>] ftrace_make_nop+0x3c/0x58
[ 32.033532] [<fffffe0000164420>] ftrace_process_locs+0x3d0/0x5c8
[ 32.033709] [<fffffe00001661cc>] ftrace_module_init+0x28/0x34
[ 32.033882] [<fffffe0000135148>] load_module+0xbb8/0xfc4
[ 32.034044] [<fffffe0000135714>] SyS_finit_module+0x94/0xc4
[...]
This is triggered by the use of virt_to_page() on a module address,
which ends to pointing to Nowhereland if you're lucky, or corrupt
your precious data if not.
This patch fixes the logic by mimicking what is done on arm:
- If we're patching a module and CONFIG_DEBUG_SET_MODULE_RONX is set,
use vmalloc_to_page().
- If we're patching the kernel and CONFIG_DEBUG_RODATA is set,
use virt_to_page().
- Otherwise, use the provided address, as we can write to it directly.
Tested on 4.0-rc1 as a KVM guest.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Laura Abbott <lauraa@codeaurora.org>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r-- | arch/arm64/kernel/insn.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c index 27d4864577e5..c8eca88f12e6 100644 --- a/arch/arm64/kernel/insn.c +++ b/arch/arm64/kernel/insn.c @@ -87,8 +87,10 @@ static void __kprobes *patch_map(void *addr, int fixmap) if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) page = vmalloc_to_page(addr); - else + else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA)) page = virt_to_page(addr); + else + return addr; BUG_ON(!page); set_fixmap(fixmap, page_to_phys(page)); |