From: Andrew Morton <akpm@linux-foundation.org>
To: willy@infradead.org, vbabka@suse.cz, sumit.semwal@linaro.org,
sashal@kernel.org, pcc@google.com, mhocko@suse.com,
legion@kernel.org, kirill.shutemov@linux.intel.com,
keescook@chromium.org, hannes@cmpxchg.org, gorcunov@gmail.com,
ebiederm@xmission.com, david@redhat.com, dave@stgolabs.net,
dave.hansen@intel.com, chris.hyser@oracle.com, ccross@google.com,
caoxiaofeng@yulong.com, brauner@kernel.org, surenb@google.com,
akpm@linux-foundation.org, patches@lists.linux.dev,
linux-mm@kvack.org, mm-commits@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org
Subject: [patch 4/8] mm: fix use-after-free when anon vma name is used after vma is freed
Date: Fri, 04 Mar 2022 20:28:58 -0800 [thread overview]
Message-ID: <20220305042859.13555C340F1@smtp.kernel.org> (raw)
In-Reply-To: <20220304202822.d47f8084928321c83070d7d7@linux-foundation.org>
From: Suren Baghdasaryan <surenb@google.com>
Subject: mm: fix use-after-free when anon vma name is used after vma is freed
When adjacent vmas are being merged it can result in the vma that was
originally passed to madvise_update_vma being destroyed. In the current
implementation, the name parameter passed to madvise_update_vma points
directly to vma->anon_name and it is used after the call to vma_merge. In
the cases when vma_merge merges the original vma and destroys it, this
might result in UAF. For that the original vma would have to hold the
anon_vma_name with the last reference. The following vma would need to
contain a different anon_vma_name object with the same string. Such
scenario is shown below:
madvise_vma_behavior(vma)
madvise_update_vma(vma, ..., anon_name == vma->anon_name)
vma_merge(vma)
__vma_adjust(vma) <-- merges vma with adjacent one
vm_area_free(vma) <-- frees the original vma
replace_vma_anon_name(anon_name) <-- UAF of vma->anon_name
Fix this by raising the name refcount and stabilizing it.
Link: https://lkml.kernel.org/r/20220224231834.1481408-3-surenb@google.com
Link: https://lkml.kernel.org/r/20220223153613.835563-3-surenb@google.com
Fixes: 9a10064f5625 ("mm: add a field to store names for private anonymous memory")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reported-by: syzbot+aa7b3d4b35f9dc46a366@syzkaller.appspotmail.com
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Chris Hyser <chris.hyser@oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Colin Cross <ccross@google.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xiaofeng Cao <caoxiaofeng@yulong.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/madvise.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/mm/madvise.c~mm-fix-use-after-free-when-anon-vma-name-is-used-after-vma-is-freed
+++ a/mm/madvise.c
@@ -131,6 +131,8 @@ static int replace_anon_vma_name(struct
/*
* Update the vm_flags on region of a vma, splitting it or merging it as
* necessary. Must be called with mmap_sem held for writing;
+ * Caller should ensure anon_name stability by raising its refcount even when
+ * anon_name belongs to a valid vma because this function might free that vma.
*/
static int madvise_update_vma(struct vm_area_struct *vma,
struct vm_area_struct **prev, unsigned long start,
@@ -945,6 +947,7 @@ static int madvise_vma_behavior(struct v
unsigned long behavior)
{
int error;
+ struct anon_vma_name *anon_name;
unsigned long new_flags = vma->vm_flags;
switch (behavior) {
@@ -1010,8 +1013,11 @@ static int madvise_vma_behavior(struct v
break;
}
+ anon_name = anon_vma_name(vma);
+ anon_vma_name_get(anon_name);
error = madvise_update_vma(vma, prev, start, end, new_flags,
- anon_vma_name(vma));
+ anon_name);
+ anon_vma_name_put(anon_name);
out:
/*
_
next prev parent reply other threads:[~2022-03-05 4:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-05 4:28 incoming Andrew Morton
2022-03-05 4:28 ` [patch 1/8] selftests/vm: cleanup hugetlb file after mremap test Andrew Morton
2022-03-05 4:28 ` [patch 2/8] mm: refactor vm_area_struct::anon_vma_name usage code Andrew Morton
2022-03-05 4:28 ` [patch 3/8] mm: prevent vm_area_struct::anon_name refcount saturation Andrew Morton
2022-03-05 19:03 ` Linus Torvalds
2022-03-05 4:28 ` Andrew Morton [this message]
2022-03-05 4:29 ` [patch 5/8] memfd: fix F_SEAL_WRITE after shmem huge page allocated Andrew Morton
2022-03-05 4:29 ` [patch 6/8] kselftest/vm: fix tests build with old libc Andrew Morton
2022-03-05 4:29 ` [patch 7/8] proc: fix documentation and description of pagemap Andrew Morton
2022-03-05 4:29 ` [patch 8/8] configs/debug: set CONFIG_DEBUG_INFO=y properly Andrew Morton
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