linux-kernel - [PATCHv3 perf/core 01/22] uprobes: Remove breakpoint in unapply_uprobe under mmap_write

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250605132350.1488129-2-jolsa@kernel.org>
Date: Thu,  5 Jun 2025 15:23:28 +0200
From: Jiri Olsa <jolsa@...nel.org>
To: Oleg Nesterov <oleg@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrii Nakryiko <andrii@...nel.org>
Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	x86@...nel.org,
	Song Liu <songliubraving@...com>,
	Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>,
	Hao Luo <haoluo@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Alan Maguire <alan.maguire@...cle.com>,
	David Laight <David.Laight@...LAB.COM>,
	Thomas Weißschuh <thomas@...ch.de>,
	Ingo Molnar <mingo@...nel.org>
Subject: [PATCHv3 perf/core 01/22] uprobes: Remove breakpoint in unapply_uprobe under mmap_write_lock

Currently unapply_uprobe takes mmap_read_lock, but it might call
remove_breakpoint which eventually changes user pages.

Current code writes either breakpoint or original instruction, so it can
go away with read lock as explained in here [1]. But with the upcoming
change that writes multiple instructions on the probed address we need
to ensure that any update to mm's pages is exclusive.

[1] https://lore.kernel.org/all/20240710140045.GA1084@redhat.com/

Acked-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/events/uprobes.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 84ee7b590861..257581432cd8 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -483,7 +483,7 @@ static int __uprobe_write_opcode(struct vm_area_struct *vma,
  * @opcode_vaddr: the virtual address to store the opcode.
  * @opcode: opcode to be written at @opcode_vaddr.
  *
- * Called with mm->mmap_lock held for read or write.
+ * Called with mm->mmap_lock held for write.
  * Return 0 (success) or a negative errno.
  */
 int uprobe_write_opcode(struct arch_uprobe *auprobe, struct vm_area_struct *vma,
@@ -1464,7 +1464,7 @@ static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
 	struct vm_area_struct *vma;
 	int err = 0;
 
-	mmap_read_lock(mm);
+	mmap_write_lock(mm);
 	for_each_vma(vmi, vma) {
 		unsigned long vaddr;
 		loff_t offset;
@@ -1481,7 +1481,7 @@ static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
 		vaddr = offset_to_vaddr(vma, uprobe->offset);
 		err |= remove_breakpoint(uprobe, vma, vaddr);
 	}
-	mmap_read_unlock(mm);
+	mmap_write_unlock(mm);
 
 	return err;
 }
-- 
2.49.0