Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'x86-urgent-2020-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into master
Pull x86 fixes from Ingo Molnar:
"Misc fixes:
- Fix a section end page alignment assumption that was causing
crashes
- Fix ORC unwinding on freshly forked tasks which haven't executed
yet and which have empty user task stacks
- Fix the debug.exception-trace=1 sysctl dumping of user stacks,
which was broken by recent maccess changes"
* tag 'x86-urgent-2020-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/dumpstack: Dump user space code correctly again
x86/stacktrace: Fix reliable check for empty user task stacks
x86/unwind/orc: Fix ORC for newly forked tasks
x86, vmlinux.lds: Page-align end of ..page_aligned sections
+28
-18
+17
-10
arch/x86/kernel/dumpstack.c
+17
-10
arch/x86/kernel/dumpstack.c
···
71
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printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
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}
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+
static int copy_code(struct pt_regs *regs, u8 *buf, unsigned long src,
75
+
unsigned int nbytes)
76
+
{
77
+
if (!user_mode(regs))
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+
return copy_from_kernel_nofault(buf, (u8 *)src, nbytes);
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+
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+
/*
81
+
* Make sure userspace isn't trying to trick us into dumping kernel
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+
* memory by pointing the userspace instruction pointer at it.
83
+
*/
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+
if (__chk_range_not_ok(src, nbytes, TASK_SIZE_MAX))
85
+
return -EINVAL;
86
+
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+
return copy_from_user_nmi(buf, (void __user *)src, nbytes);
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+
}
89
+
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/*
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* There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
76
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*
···
113
97
#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
114
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u8 opcodes[OPCODE_BUFSIZE];
115
99
unsigned long prologue = regs->ip - PROLOGUE_SIZE;
116
-
bool bad_ip;
117
100
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-
/*
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-
* Make sure userspace isn't trying to trick us into dumping kernel
120
-
* memory by pointing the userspace instruction pointer at it.
121
-
*/
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-
bad_ip = user_mode(regs) &&
123
-
__chk_range_not_ok(prologue, OPCODE_BUFSIZE, TASK_SIZE_MAX);
124
-
125
-
if (bad_ip || copy_from_kernel_nofault(opcodes, (u8 *)prologue,
126
-
OPCODE_BUFSIZE)) {
101
+
if (copy_code(regs, opcodes, prologue, sizeof(opcodes))) {
127
102
printk("%sCode: Bad RIP value.\n", loglvl);
128
103
} else {
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printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
-5
arch/x86/kernel/stacktrace.c
-5
arch/x86/kernel/stacktrace.c
···
58
58
* or a page fault), which can make frame pointers
59
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* unreliable.
60
60
*/
61
-
62
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if (IS_ENABLED(CONFIG_FRAME_POINTER))
63
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return -EINVAL;
64
63
}
···
78
79
79
80
/* Check for stack corruption */
80
81
if (unwind_error(&state))
81
-
return -EINVAL;
82
-
83
-
/* Success path for non-user tasks, i.e. kthreads and idle tasks */
84
-
if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
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return -EINVAL;
86
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return 0;
+6
-2
arch/x86/kernel/unwind_orc.c
+6
-2
arch/x86/kernel/unwind_orc.c
···
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/*
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* Find the orc_entry associated with the text address.
442
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*
443
-
* Decrement call return addresses by one so they work for sibling
444
-
* calls and calls to noreturn functions.
443
+
* For a call frame (as opposed to a signal frame), state->ip points to
444
+
* the instruction after the call. That instruction's stack layout
445
+
* could be different from the call instruction's layout, for example
446
+
* if the call was to a noreturn function. So get the ORC data for the
447
+
* call instruction itself.
445
448
*/
446
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orc = orc_find(state->signal ? state->ip : state->ip - 1);
447
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if (!orc) {
···
665
662
state->sp = task->thread.sp;
666
663
state->bp = READ_ONCE_NOCHECK(frame->bp);
667
664
state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
665
+
state->signal = (void *)state->ip == ret_from_fork;
668
666
}
669
667
670
668
if (get_stack_info((unsigned long *)state->sp, state->task,
+1
arch/x86/kernel/vmlinux.lds.S
+1
arch/x86/kernel/vmlinux.lds.S
+4
-1
include/asm-generic/vmlinux.lds.h
+4
-1
include/asm-generic/vmlinux.lds.h
···
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#define PAGE_ALIGNED_DATA(page_align) \
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. = ALIGN(page_align); \
344
-
*(.data..page_aligned)
344
+
*(.data..page_aligned) \
345
+
. = ALIGN(page_align);
345
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347
#define READ_MOSTLY_DATA(align) \
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. = ALIGN(align); \
···
738
737
. = ALIGN(bss_align); \
739
738
.bss : AT(ADDR(.bss) - LOAD_OFFSET) { \
740
739
BSS_FIRST_SECTIONS \
740
+
. = ALIGN(PAGE_SIZE); \
741
741
*(.bss..page_aligned) \
742
+
. = ALIGN(PAGE_SIZE); \
742
743
*(.dynbss) \
743
744
*(BSS_MAIN) \
744
745
*(COMMON) \