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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id x14-20020a170902a38e00b0019604f3fc3asm77929pla.265.2023.02.02.12.43.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Feb 2023 12:43:05 -0800 (PST) Message-ID: <63dc2059.170a0220.25fcc.0394@mx.google.com> X-Google-Original-Message-ID: <202302022041.@keescook> Date: Thu, 2 Feb 2023 20:43:04 +0000 From: Kees Cook To: Sami Tolvanen Cc: Nick Desaulniers , Ard Biesheuvel , John Stultz , Yongqin Liu , Vlastimil Babka , Greg Kroah-Hartman , Rasmus Villemoes , Thomas Gleixner , Jason Gunthorpe , Nishanth Menon , Michael Kelley , Dan Williams , Won Chung , David Gow , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Guenter Roeck , Andy Shevchenko , Paolo Abeni , Geert Uytterhoeven , Nathan Chancellor , Tom Rix , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, llvm@lists.linux.dev, Sumit Semwal Subject: Re: [PATCH 5/6] driver core: Add __alloc_size hint to devm allocators References: <63dbf04a.630a0220.2608a.0149@mx.google.com> <63dc0a89.170a0220.49507.0091@mx.google.com> <63dc14a2.170a0220.beb2a.0275@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: F388516000E X-Stat-Signature: cue5nmx5gzswk16s4hhwocdak85zg84b X-Rspam-User: X-HE-Tag: 1675370586-403719 X-HE-Meta: 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 VtgCIjIm 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 02, 2023 at 12:11:47PM -0800, Sami Tolvanen wrote: > On Thu, Feb 2, 2023 at 11:53 AM Kees Cook wrote: > > > > On Thu, Feb 02, 2023 at 11:49:42AM -0800, Sami Tolvanen wrote: > > > A quick look at Clang's source code suggests that Intrinsic::ubsantrap > > > already accepts the handler ID (from the SanitizerHandler enum) as an > > > argument and the arm64 LLVM back-end appears to encode the value as an > > > immediate for the brk instruction. I didn't confirm that this actually > > > works, but perhaps we just need to teach the kernel about the possible > > > values? > > > > Oh excellent. Yeah, if that's all that's needed here that would be > > great. What are the values? > > The arm64 brk immediate encoding seems to be "ubsantrap arg | 'U' << 8": > > https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/AArch64/AArch64InstrInfo.td#L7571 > > The argument values come from the SanitizerHandler enum, which is > populated from this list: > > https://github.com/llvm/llvm-project/blob/main/clang/lib/CodeGen/CodeGenFunction.h#L113 > > Therefore, according to the tests, for ubsantrap(12) we'll get brk > #0x550c, for example: > > https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/AArch64/ubsantrap.ll So the absolute minimal handler would look like this: diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h index 6e000113e508..3f0f0d03268b 100644 --- a/arch/arm64/include/asm/brk-imm.h +++ b/arch/arm64/include/asm/brk-imm.h @@ -28,6 +28,8 @@ #define BUG_BRK_IMM 0x800 #define KASAN_BRK_IMM 0x900 #define KASAN_BRK_MASK 0x0ff +#define UBSAN_BRK_IMM 0x5500 +#define UBSAN_BRK_MASK 0x00ff #define CFI_BRK_IMM_TARGET GENMASK(4, 0) #define CFI_BRK_IMM_TYPE GENMASK(9, 5) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 4c0caa589e12..36b917d8fa5f 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -1074,6 +1074,18 @@ static struct break_hook kasan_break_hook = { }; #endif +#ifdef CONFIG_UBSAN_TRAP +static int ubsan_handler(struct pt_regs *regs, unsigned long esr) +{ + die("Oops - UBSAN", regs, esr); +} + +static struct break_hook ubsan_break_hook = { + .fn = ubsan_handler, + .imm = UBSAN_BRK_IMM, + .mask = UBSAN_BRK_MASK, +}; +#endif #define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) @@ -1091,6 +1103,10 @@ int __init early_brk64(unsigned long addr, unsigned long esr, #ifdef CONFIG_KASAN_SW_TAGS if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; +#endif +#ifdef CONFIG_UBSAN_TRAP + if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) + return ubsan_handler(regs, esr) != DBG_HOOK_HANDLED; #endif return bug_handler(regs, esr) != DBG_HOOK_HANDLED; } @@ -1104,6 +1120,9 @@ void __init trap_init(void) register_kernel_break_hook(&fault_break_hook); #ifdef CONFIG_KASAN_SW_TAGS register_kernel_break_hook(&kasan_break_hook); +#endif +#ifdef CONFIG_UBSAN_TRAP + register_kernel_break_hook(&ubsan_break_hook); #endif debug_traps_init(); } But we could expand ubsan_handler() to extract the SanitizerHandler enum value and report which UBSAN check was hit... -- Kees Cook