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Message-ID: <CAMo8Bf+RKVpYT309ystJKVHDqDaK4ZavGe3e-a_jvG7AOcqciw@mail.gmail.com> Date: Mon, 12 Aug 2024 11:02:42 -0700 From: Max Filippov <jcmvbkbc@...il.com> To: Greg Ungerer <gregungerer@...tnet.com.au> Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, linux-fsdevel@...r.kernel.org, Eric Biederman <ebiederm@...ssion.com>, Kees Cook <keescook@...omium.org>, Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz> Subject: Re: [PATCH] binfmt_elf_fdpic: fix /proc/<pid>/auxv Hi Greg, On Sun, Aug 11, 2024 at 7:26 PM Greg Ungerer <gregungerer@...tnet.com.au> wrote: > On 23/3/24 05:54, Max Filippov wrote: > > Althought FDPIC linux kernel provides /proc/<pid>/auxv files they are > > empty because there's no code that initializes mm->saved_auxv in the > > FDPIC ELF loader. > > > > Synchronize FDPIC ELF aux vector setup with ELF. Replace entry-by-entry > > aux vector copying to userspace with initialization of mm->saved_auxv > > first and then copying it to userspace as a whole. > > > > Signed-off-by: Max Filippov <jcmvbkbc@...il.com> > > This is breaking ARM nommu builds supporting fdpic and elf binaries for me. > > Tests I have for m68k and riscv nommu setups running elf binaries > don't show any problems - I am only seeing this on ARM. > > > ... > Freeing unused kernel image (initmem) memory: 472K > This architecture does not have kernel memory protection. > Run /init as init process > Internal error: Oops - undefined instruction: 0 [#1] ARM > Modules linked in: > CPU: 0 PID: 1 Comm: init Not tainted 6.10.0 #1 > Hardware name: ARM-Versatile (Device Tree Support) > PC is at load_elf_fdpic_binary+0xb34/0xb80 > LR is at 0x0 > pc : [<00109ce8>] lr : [<00000000>] psr: 80000153 > sp : 00823e40 ip : 00000000 fp : 00b8fee4 > r10: 009c9b80 r9 : 00b8ff80 r8 : 009ee800 > r7 : 00000000 r6 : 009f7e80 r5 : 00b8fedc r4 : 00b87000 > r3 : 00b8fed8 r2 : 00b8fee0 r1 : 00b87128 r0 : 00b8fef0 > Flags: Nzcv IRQs on FIQs off Mode SVC_32 ISA ARM Segment none > Control: 00091176 Table: 00000000 DAC: 00000000 > Register r0 information: non-slab/vmalloc memory > Register r1 information: slab/vmalloc mm_struct start 00b87000 pointer offset 296 size 428 > Register r2 information: non-slab/vmalloc memory > Register r3 information: non-slab/vmalloc memory > Register r4 information: slab/vmalloc mm_struct start 00b87000 pointer offset 0 size 428 > Register r5 information: non-slab/vmalloc memory > Register r6 information: slab/vmalloc kmalloc-32 start 009f7e80 pointer offset 0 size 32 > Register r7 information: non-slab/vmalloc memory > Register r8 information: slab/vmalloc kmalloc-512 start 009ee800 pointer offset 0 size 512 > Register r9 information: non-slab/vmalloc memory > Register r10 information: slab/vmalloc kmalloc-128 start 009c9b80 pointer offset 0 size 128 > Register r11 information: non-slab/vmalloc memory > Register r12 information: non-slab/vmalloc memory > Process init (pid: 1, stack limit = 0x(ptrval)) > Stack: (0x00823e40 to 0x00824000) > 3e40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3e60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3e80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3ea0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3ec0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3ee0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3f00: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3f20: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3f40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3f60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3f80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3fa0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3fe0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > Call trace: > load_elf_fdpic_binary from bprm_execve+0x1b4/0x488 > bprm_execve from kernel_execve+0x154/0x1e4 > kernel_execve from kernel_init+0x4c/0x108 > kernel_init from ret_from_fork+0x14/0x38 > Exception stack(0x00823fb0 to 0x00823ff8) > 3fa0: ???????? ???????? ???????? ???????? > 3fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ???????? > 3fe0: ???????? ???????? ???????? ???????? ???????? ???????? > Code: bad PC value > ---[ end trace 0000000000000000 ]--- > note: init[1] exited with irqs disabled > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- > > > The code around that PC is: > > 109cd0: e2833ff1 add r3, r3, #964 @ 0x3c4 > 109cd4: e5933000 ldr r3, [r3] > 109cd8: e5933328 ldr r3, [r3, #808] @ 0x328 > 109cdc: e5933084 ldr r3, [r3, #132] @ 0x84 > 109ce0: e5843034 str r3, [r4, #52] @ 0x34 > 109ce4: eafffdbc b 1093dc <load_elf_fdpic_binary+0x228> > 109ce8: e7f001f2 .word 0xe7f001f2 > 109cec: eb09471d bl 35b968 <__stack_chk_fail> > 109cf0: e59f0038 ldr r0, [pc, #56] @ 109d30 <load_elf_fdpic_binary+0xb7c> > 109cf4: eb092f03 bl 355908 <_printk> > 109cf8: eafffdb7 b 1093dc <load_elf_fdpic_binary+0x228> > > > Reverting just this change gets it working again. > > Any idea what might be going on? Other than that the layout of the aux vector has slightly changed I don't see anything. I can take a look at what's going on if you can share the reproducer. -- Thanks. -- Max
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