| Message ID | 1602002973-92934-1-git-send-email-guoren@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv: Fixup bootup failure with HARDENED_USERCOPY | expand |
On Tue, 06 Oct 2020 09:49:33 PDT (-0700), guoren@kernel.org wrote: > From: Guo Ren <guoren@linux.alibaba.com> > > 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 <palmer@dabbelt.com>" [ultimate] gpg: aka "Palmer Dabbelt <palmerdabbelt@google.com>" [ultimate] Author: Guo Ren <guoren@linux.alibaba.com> 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. Link: https://lore.kernel.org/linux-riscv/1593266228-61125-1-git-send-email-guoren@kernel.org/T/#t Signed-off-by: Guo Ren <guoren@linux.alibaba.com> Reported-by: Aurelien Jarno <aurelien@aurel32.net> Tested-by: Aurelien Jarno <aurelien@aurel32.net> [Palmer: Clean up commit text] Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> > 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 <guoren@linux.alibaba.com> > Reported-by: Aurelien Jarno <aurelien@aurel32.net> > Tested-by: Aurelien Jarno <aurelien@aurel32.net> > Cc: Palmer Dabbelt <palmerdabbelt@google.com> > Cc: Atish Patra <atishp@atishpatra.org> > Cc: Andreas Schwab <schwab@linux-m68k.org> > --- > 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)
On Tue, Oct 6, 2020 at 9:12 PM Palmer Dabbelt <palmerdabbelt@google.com> wrote: > > On Tue, 06 Oct 2020 09:49:33 PDT (-0700), guoren@kernel.org wrote: > > From: Guo Ren <guoren@linux.alibaba.com> > > > > 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 <palmer@dabbelt.com>" [ultimate] > gpg: aka "Palmer Dabbelt <palmerdabbelt@google.com>" [ultimate] > Author: Guo Ren <guoren@linux.alibaba.com> > 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 <guoren@linux.alibaba.com> > Reported-by: Aurelien Jarno <aurelien@aurel32.net> > Tested-by: Aurelien Jarno <aurelien@aurel32.net> > [Palmer: Clean up commit text] > Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> > > > 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 <guoren@linux.alibaba.com> > > Reported-by: Aurelien Jarno <aurelien@aurel32.net> > > Tested-by: Aurelien Jarno <aurelien@aurel32.net> > > Cc: Palmer Dabbelt <palmerdabbelt@google.com> > > Cc: Atish Patra <atishp@atishpatra.org> > > Cc: Andreas Schwab <schwab@linux-m68k.org> > > --- > > 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)
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)