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Revert "uprobes: use vm_special_mapping close() functionality"

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This reverts commit 08e28de116.

A malicious application can munmap() its "[uprobes]" vma and in this case
xol_mapping.close == uprobe_clear_state() will free the memory which can
be used by another thread, or the same thread when it hits the uprobe bp
afterwards.

Link: https://lkml.kernel.org/r/20240911131320.GA3448@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2024-09-11 15:13:20 +02:00 committed by Andrew Morton
parent 242d12c981
commit ed8d5b0ce1
3 changed files with 21 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/uprobes.h
View File

@ -126,6 +126,7 @@ extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
extern void uprobe_notify_resume(struct pt_regs *regs);
extern bool uprobe_deny_signal(void);
extern bool arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
extern void uprobe_clear_state(struct mm_struct *mm);
extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);

36
kernel/events/uprobes.c
View File

@ -1482,22 +1482,6 @@ void * __weak arch_uprobe_trampoline(unsigned long *psize)
return &insn;
}
/*
* uprobe_clear_state - Free the area allocated for slots.
*/
static void uprobe_clear_state(const struct vm_special_mapping *sm, struct vm_area_struct *vma)
{
struct xol_area *area = container_of(vma->vm_private_data, struct xol_area, xol_mapping);
mutex_lock(&delayed_uprobe_lock);
delayed_uprobe_remove(NULL, vma->vm_mm);
mutex_unlock(&delayed_uprobe_lock);
put_page(area->pages[0]);
kfree(area->bitmap);
kfree(area);
}
static struct xol_area *__create_xol_area(unsigned long vaddr)
{
struct mm_struct *mm = current->mm;
@ -1516,7 +1500,6 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
area->xol_mapping.name = "[uprobes]";
area->xol_mapping.fault = NULL;
area->xol_mapping.close = uprobe_clear_state;
area->xol_mapping.pages = area->pages;
area->pages[0] = alloc_page(GFP_HIGHUSER);
if (!area->pages[0])
@ -1562,6 +1545,25 @@ static struct xol_area *get_xol_area(void)
return area;
}
/*
* uprobe_clear_state - Free the area allocated for slots.
*/
void uprobe_clear_state(struct mm_struct *mm)
{
struct xol_area *area = mm->uprobes_state.xol_area;
mutex_lock(&delayed_uprobe_lock);
delayed_uprobe_remove(NULL, mm);
mutex_unlock(&delayed_uprobe_lock);
if (!area)
return;
put_page(area->pages[0]);
kfree(area->bitmap);
kfree(area);
}
void uprobe_start_dup_mmap(void)
{
percpu_down_read(&dup_mmap_sem);

1
kernel/fork.c
View File

@ -1338,6 +1338,7 @@ static inline void __mmput(struct mm_struct *mm)
{
VM_BUG_ON(atomic_read(&mm->mm_users));
uprobe_clear_state(mm);
exit_aio(mm);
ksm_exit(mm);
khugepaged_exit(mm); /* must run before exit_mmap */