The patch titled
Subject: Revert "uprobes: use vm_special_mapping close() functionality"
has been added to the -mm mm-unstable branch. Its filename is
revert-uprobes-use-vm_special_mapping-close-functionality.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/revert-uprobes-use-vm_special_mapping-close-functionality.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: Revert "uprobes: use vm_special_mapping close() functionality"
Date: Wed, 11 Sep 2024 15:13:20 +0200
This reverts commit 08e28de1160a712724268fd33d77b32f1bc84d1c.
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@xxxxxxxxxx
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/uprobes.h | 1 +
kernel/events/uprobes.c | 36 +++++++++++++++++++-----------------
kernel/fork.c | 1 +
3 files changed, 21 insertions(+), 17 deletions(-)
--- a/include/linux/uprobes.h~revert-uprobes-use-vm_special_mapping-close-functionality
+++ a/include/linux/uprobes.h
@@ -126,6 +126,7 @@ extern int uprobe_pre_sstep_notifier(str
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);
--- a/kernel/events/uprobes.c~revert-uprobes-use-vm_special_mapping-close-functionality
+++ a/kernel/events/uprobes.c
@@ -1482,22 +1482,6 @@ void * __weak arch_uprobe_trampoline(uns
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_are
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(voi
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);
--- a/kernel/fork.c~revert-uprobes-use-vm_special_mapping-close-functionality
+++ a/kernel/fork.c
@@ -1338,6 +1338,7 @@ static inline void __mmput(struct mm_str
{
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 */
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
revert-uprobes-use-vm_special_mapping-close-functionality.patch
uprobes-introduce-the-global-struct-vm_special_mapping-xol_mapping.patch
uprobes-turn-xol_area-pages-into-xol_area-page.patch
