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bh=xi1LOdmOzzyOAIKt3+WaGpmoC5ZmXljmCt0LFHCFgaM=; b=Ger2gFTNupebqrJ/G3XIDyhNktTDRPaCk1cPRzi94pOr2Nh0gRbhCMAk45cnDgbMTo HwVH4XZ9fLrOE2N2P0NmP8hwcct59YpCw6Z161g6qQKP4Ef+htY+KybPA8N/aHatpZG+ O3LRJMyqIoizj80c+WXXsjWd4qBPKaluDp4reRC66wBLTl8x88mlbt0uaNaslVkcdFb1 UJYfam0NZRwalvPKuq6HmTXHkmyZCUM8tBf8RIUYsoXi0jsyoDcc34FoF8WnPBWTVN+O VivFg3MhQfoYOoffvZoIcw2enWm9zfKMPZT3ZC9dtwXg7hLuBTFrkyf0fBh0lqnwWnmq SlCA== X-Gm-Message-State: AOAM533j0d+XS6v+9iElv/pkl3+kgKDPzhQHyDlEYCJ9qYdYlk3Zr/bG gkWjUqBk6TGQfnmglx0BCXn6osK3+QpenSSsLVDg X-Google-Smtp-Source: ABdhPJz2TmwP3z4c7sr6ej/YTwPX+d9QyUpD3prBxDMpPWTVe9zH7d8FxWe+L5MdzSFijnn/zVngkOlGs0Ids0u4dKs= X-Received: by 2002:a5d:84c6:: with SMTP id z6mr1345226ior.0.1602054743520; Wed, 07 Oct 2020 00:12:23 -0700 (PDT) MIME-Version: 1.0 References: <1602002973-92934-1-git-send-email-guoren@kernel.org> In-Reply-To: From: Atish Patra Date: Wed, 7 Oct 2020 00:12:10 -0700 Message-ID: Subject: Re: [PATCH] riscv: Fixup bootup failure with HARDENED_USERCOPY To: Palmer Dabbelt X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201007_031225_951311_D88E7E99 X-CRM114-Status: GOOD ( 32.87 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andreas Schwab , linux-riscv , Guo Ren , Guo Ren , "linux-kernel@vger.kernel.org List" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Tue, Oct 6, 2020 at 9:12 PM Palmer Dabbelt wrote: > > On Tue, 06 Oct 2020 09:49:33 PDT (-0700), guoren@kernel.org wrote: > > From: Guo Ren > > > > As Aurelien has reported: > > > > [ 3.484586] AppArmor: AppArmor sha1 policy hashing enabled > > [ 4.749835] Freeing unused kernel memory: 492K > > [ 4.752017] Run /init as init process > > [ 4.753571] usercopy: Kernel memory overwrite attempt detected to kernel text (offset 507879, size 11)! > > [ 4.754838] ------------[ cut here ]------------ > > [ 4.755651] kernel BUG at mm/usercopy.c:99! > > [ 4.756445] Kernel BUG [#1] > > [ 4.756815] Modules linked in: > > [ 4.757542] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.8.0-1-riscv64 #1 Debian 5.8.7-1 > > [ 4.758372] epc: ffffffe0003b5120 ra : ffffffe0003b5120 sp : ffffffe07f783ca0 > > [ 4.758960] gp : ffffffe000cc7230 tp : ffffffe07f77cec0 t0 : ffffffe000cdafc0 > > [ 4.759772] t1 : 0000000000000064 t2 : 0000000000000000 s0 : ffffffe07f783cf0 > > [ 4.760534] s1 : ffffffe00095d780 a0 : 000000000000005b a1 : 0000000000000020 > > [ 4.761309] a2 : 0000000000000005 a3 : 0000000000000000 a4 : ffffffe000c1f340 > > [ 4.761848] a5 : ffffffe000c1f340 a6 : 0000000000000000 a7 : 0000000000000087 > > [ 4.762684] s2 : ffffffe000941848 s3 : 000000000007bfe7 s4 : 000000000000000b > > [ 4.763500] s5 : 0000000000000000 s6 : ffffffe00091cc00 s7 : fffffffffffff000 > > [ 4.764376] s8 : 0000003ffffff000 s9 : ffffffe0769f3200 s10: 000000000000000b > > [ 4.765208] s11: ffffffe07d548c40 t3 : 0000000000000000 t4 : 000000000001dcd0 > > [ 4.766059] t5 : ffffffe000cc8510 t6 : ffffffe000cd64aa > > [ 4.766712] status: 0000000000000120 badaddr: 0000000000000000 cause: 0000000000000003 > > [ 4.768308] ---[ end trace 1f8e733e834d4c3e ]--- > > [ 4.769129] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > > [ 4.770070] SMP: stopping secondary CPUs > > [ 4.771110] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- > > > > Above failure is relate to commit: a0fa4027dc911 (riscv: Fixup > > That commit isn't in Linus' tree (at least, as far as I see it). I have > 6184358da000 ("riscv: Fixup static_obj() fail"), so I'm going to fix that -- in > fact, I'm going to essentially just replace most of this rationale with what I > wrote up in my revert as this is all a bit too long for a commit message. > > I was kind of worried the initdata move was a bit too risky, but after reading > the users of __init_{begin,end} I think it's safe. Here's what I ended up with > on fixes. > > Thanks! > > commit 84814460eef9af0fb56a4698341c9cb7996a6312 (HEAD -> fixes, riscv/fixes) > gpg: Signature made Tue 06 Oct 2020 09:11:35 PM PDT > gpg: using RSA key 2B3C3747446843B24A943A7A2E1319F35FBB1889 > gpg: issuer "palmer@dabbelt.com" > gpg: Good signature from "Palmer Dabbelt " [ultimate] > gpg: aka "Palmer Dabbelt " [ultimate] > Author: Guo Ren > Date: Tue Oct 6 16:49:33 2020 +0000 > > riscv: Fixup bootup failure with HARDENED_USERCOPY > > 6184358da000 ("riscv: Fixup static_obj() fail") attempted to elide a lockdep > failure by rearranging our kernel image to place all initdata within [_stext, > _end], thus triggering lockdep to treat these as static objects. These objects > are released and eventually reallocated, causing check_kernel_text_object() to > trigger a BUG(). > > This backs out the change to make [_stext, _end] all-encompassing, instead just > moving initdata. This results in initdata being outside of [__init_begin, > __init_end], which means initdata can't be freed. > But we are not moving all initdata out of __init_begin/end. Should we move all the _initdata section out of _init_begin ? http://lists.infradead.org/pipermail/linux-riscv/2020-October/002400.html > Link: https://lore.kernel.org/linux-riscv/1593266228-61125-1-git-send-email-guoren@kernel.org/T/#t > Signed-off-by: Guo Ren > Reported-by: Aurelien Jarno > Tested-by: Aurelien Jarno > [Palmer: Clean up commit text] > Signed-off-by: Palmer Dabbelt > > > static_obj() fail). When we expand static_obj include INIT_DATA, > > we also include INIT_TEXT into usercopy check kernel text: > > > > /* Is this address range in the kernel text area? */ > > static inline void check_kernel_text_object(const unsigned long ptr, > > unsigned long n, bool to_user) > > { > > unsigned long textlow = (unsigned long)_stext; > > unsigned long texthigh = (unsigned long)_etext; > > unsigned long textlow_linear, texthigh_linear; > > > > if (overlaps(ptr, n, textlow, texthigh)) > > usercopy_abort("kernel text", NULL, to_user, ptr - textlow, n); > > > > When INIT_TEXT/DATA are freed, new allocation will reuse these > > memory and overlaps check will be triggered. > > > > The patch met static_obj and check_kernel_text_object requirements. > > > > Link: https://lore.kernel.org/linux-riscv/1593266228-61125-1-git-send-email-guoren@kernel.org/T/#t > > Signed-off-by: Guo Ren > > Reported-by: Aurelien Jarno > > Tested-by: Aurelien Jarno > > Cc: Palmer Dabbelt > > Cc: Atish Patra > > Cc: Andreas Schwab > > --- > > arch/riscv/kernel/vmlinux.lds.S | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S > > index f3586e3..34d00d9 100644 > > --- a/arch/riscv/kernel/vmlinux.lds.S > > +++ b/arch/riscv/kernel/vmlinux.lds.S > > @@ -22,13 +22,11 @@ SECTIONS > > /* Beginning of code and text segment */ > > . = LOAD_OFFSET; > > _start = .; > > - _stext = .; > > HEAD_TEXT_SECTION > > . = ALIGN(PAGE_SIZE); > > > > __init_begin = .; > > INIT_TEXT_SECTION(PAGE_SIZE) > > - INIT_DATA_SECTION(16) > > . = ALIGN(8); > > __soc_early_init_table : { > > __soc_early_init_table_start = .; > > @@ -55,6 +53,7 @@ SECTIONS > > . = ALIGN(SECTION_ALIGN); > > .text : { > > _text = .; > > + _stext = .; > > TEXT_TEXT > > SCHED_TEXT > > CPUIDLE_TEXT > > @@ -67,6 +66,8 @@ SECTIONS > > _etext = .; > > } > > > > + INIT_DATA_SECTION(16) > > + > > /* Start of data section */ > > _sdata = .; > > RO_DATA(SECTION_ALIGN) -- Regards, Atish _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv