linux-kernel - [PATCH -mm 2/3] uprobes: introduce the global struct vm_special_mapping xol

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: <20240911131407.GB3448@redhat.com>
Date: Wed, 11 Sep 2024 15:14:07 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Sven Schnelle <svens@...ux.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: Michael Ellerman <mpe@...erman.id.au>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrii Nakryiko <andrii@...nel.org>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Subject: [PATCH -mm 2/3] uprobes: introduce the global struct
 vm_special_mapping xol_mapping

Currently each xol_area has its own instance of vm_special_mapping, this
is suboptimal and ugly. Kill xol_area->xol_mapping and add a single global
instance of vm_special_mapping, the ->fault() method can use area->pages
rather than xol_mapping->pages.

As a side effect this fixes the problem introduced by the recent commit
223febc6e557 ("mm: add optional close() to struct vm_special_mapping"), if
special_mapping_close() is called from the __mmput() paths, it will use
vma->vm_private_data = &area->xol_mapping freed by uprobe_clear_state().

Reported-by: Sven Schnelle <svens@...ux.ibm.com>
Closes: https://lore.kernel.org/all/yt9dy149vprr.fsf@linux.ibm.com/
Fixes: 223febc6e557 ("mm: add optional close() to struct vm_special_mapping")
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 73cc47708679..a478e028043f 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -99,7 +99,6 @@ struct xol_area {
 	atomic_t 			slot_count;	/* number of in-use slots */
 	unsigned long 			*bitmap;	/* 0 = free slot */
 
-	struct vm_special_mapping	xol_mapping;
 	struct page 			*pages[2];
 	/*
 	 * We keep the vma's vm_start rather than a pointer to the vma
@@ -1433,6 +1432,21 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 		set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
 }
 
+static vm_fault_t xol_fault(const struct vm_special_mapping *sm,
+			    struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct xol_area *area = vma->vm_mm->uprobes_state.xol_area;
+
+	vmf->page = area->pages[0];
+	get_page(vmf->page);
+	return 0;
+}
+
+static const struct vm_special_mapping xol_mapping = {
+	.name = "[uprobes]",
+	.fault = xol_fault,
+};
+
 /* Slot allocation for XOL */
 static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
 {
@@ -1459,7 +1473,7 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
 
 	vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE,
 				VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO,
-				&area->xol_mapping);
+				&xol_mapping);
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
 		goto fail;
@@ -1498,9 +1512,6 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
 	if (!area->bitmap)
 		goto free_area;
 
-	area->xol_mapping.name = "[uprobes]";
-	area->xol_mapping.fault = NULL;
-	area->xol_mapping.pages = area->pages;
 	area->pages[0] = alloc_page(GFP_HIGHUSER);
 	if (!area->pages[0])
 		goto free_bitmap;
-- 
2.25.1.362.g51ebf55