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authorMarc Zyngier <marc.zyngier@arm.com>2015-02-24 16:30:21 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2015-02-26 18:34:27 +0000
commitf6242cac10427c546271050b31c891a078e490cd (patch)
tree71ac3ae50d0938c65f8651b26485386310931f67 /arch
parent0eee0fbd41c7b57d01136df2519c92ec1506e333 (diff)
downloadlinux-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>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kernel/insn.c4
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));