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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f4f34e1b82
When the frame unwinder is invoked for an oops caused by a call to NULL, it currently skips the parent function because BP still points to the parent's stack frame; the (nonexistent) current function only has the first half of a stack frame, and BP doesn't point to it yet. Add a special case for IP==0 that calculates a fake BP from SP, then uses the real BP for the next frame. Note that this handles first_frame specially: Return information about the parent function as long as the saved IP is >=first_frame, even if the fake BP points below it. With an artificially-added NULL call in prctl_set_seccomp(), before this patch, the trace is: Call Trace: ? prctl_set_seccomp+0x3a/0x50 __x64_sys_prctl+0x457/0x6f0 ? __ia32_sys_prctl+0x750/0x750 do_syscall_64+0x72/0x160 entry_SYSCALL_64_after_hwframe+0x44/0xa9 After this patch, the trace is: Call Trace: prctl_set_seccomp+0x3a/0x50 __x64_sys_prctl+0x457/0x6f0 ? __ia32_sys_prctl+0x750/0x750 do_syscall_64+0x72/0x160 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: syzbot <syzbot+ca95b2b7aef9e7cbd6ab@syzkaller.appspotmail.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: linux-kbuild@vger.kernel.org Link: https://lkml.kernel.org/r/20190301031201.7416-1-jannh@google.com
127 lines
3.1 KiB
C
127 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_UNWIND_H
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#define _ASM_X86_UNWIND_H
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#include <linux/sched.h>
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#include <linux/ftrace.h>
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#include <asm/ptrace.h>
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#include <asm/stacktrace.h>
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#define IRET_FRAME_OFFSET (offsetof(struct pt_regs, ip))
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#define IRET_FRAME_SIZE (sizeof(struct pt_regs) - IRET_FRAME_OFFSET)
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struct unwind_state {
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struct stack_info stack_info;
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unsigned long stack_mask;
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struct task_struct *task;
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int graph_idx;
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bool error;
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#if defined(CONFIG_UNWINDER_ORC)
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bool signal, full_regs;
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unsigned long sp, bp, ip;
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struct pt_regs *regs;
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#elif defined(CONFIG_UNWINDER_FRAME_POINTER)
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bool got_irq;
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unsigned long *bp, *orig_sp, ip;
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/*
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* If non-NULL: The current frame is incomplete and doesn't contain a
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* valid BP. When looking for the next frame, use this instead of the
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* non-existent saved BP.
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*/
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unsigned long *next_bp;
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struct pt_regs *regs;
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#else
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unsigned long *sp;
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#endif
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};
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void __unwind_start(struct unwind_state *state, struct task_struct *task,
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struct pt_regs *regs, unsigned long *first_frame);
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bool unwind_next_frame(struct unwind_state *state);
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unsigned long unwind_get_return_address(struct unwind_state *state);
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unsigned long *unwind_get_return_address_ptr(struct unwind_state *state);
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static inline bool unwind_done(struct unwind_state *state)
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{
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return state->stack_info.type == STACK_TYPE_UNKNOWN;
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}
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static inline bool unwind_error(struct unwind_state *state)
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{
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return state->error;
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}
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static inline
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void unwind_start(struct unwind_state *state, struct task_struct *task,
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struct pt_regs *regs, unsigned long *first_frame)
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{
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first_frame = first_frame ? : get_stack_pointer(task, regs);
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__unwind_start(state, task, regs, first_frame);
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}
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#if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER)
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/*
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* If 'partial' returns true, only the iret frame registers are valid.
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*/
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static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
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bool *partial)
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{
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if (unwind_done(state))
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return NULL;
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if (partial) {
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#ifdef CONFIG_UNWINDER_ORC
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*partial = !state->full_regs;
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#else
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*partial = false;
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#endif
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}
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return state->regs;
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}
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#else
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static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state,
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bool *partial)
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{
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return NULL;
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}
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#endif
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#ifdef CONFIG_UNWINDER_ORC
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void unwind_init(void);
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void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
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void *orc, size_t orc_size);
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#else
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static inline void unwind_init(void) {}
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static inline
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void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
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void *orc, size_t orc_size) {}
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#endif
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/*
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* This disables KASAN checking when reading a value from another task's stack,
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* since the other task could be running on another CPU and could have poisoned
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* the stack in the meantime.
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*/
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#define READ_ONCE_TASK_STACK(task, x) \
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({ \
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unsigned long val; \
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if (task == current) \
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val = READ_ONCE(x); \
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else \
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val = READ_ONCE_NOCHECK(x); \
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val; \
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})
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static inline bool task_on_another_cpu(struct task_struct *task)
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{
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#ifdef CONFIG_SMP
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return task != current && task->on_cpu;
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#else
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return false;
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#endif
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}
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#endif /* _ASM_X86_UNWIND_H */
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