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Message-ID: <ef2adefc6ecba82fc5b5615f459af5881ee3c013.1731946386.git.lorenzo.stoakes@oracle.com>
Date: Mon, 18 Nov 2024 16:17:26 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: stable@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Xu <peterx@...hat.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>,
"David S . Miller" <davem@...emloft.net>,
Andreas Larsson <andreas@...sler.com>,
"James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>
Subject: [PATCH 6.1.y v2 2/4] mm: unconditionally close VMAs on error
[ Upstream commit 4080ef1579b2413435413988d14ac8c68e4d42c8 ]
Incorrect invocation of VMA callbacks when the VMA is no longer in a
consistent state is bug prone and risky to perform.
With regards to the important vm_ops->close() callback We have gone to
great lengths to try to track whether or not we ought to close VMAs.
Rather than doing so and risking making a mistake somewhere, instead
unconditionally close and reset vma->vm_ops to an empty dummy operations
set with a NULL .close operator.
We introduce a new function to do so - vma_close() - and simplify existing
vms logic which tracked whether we needed to close or not.
This simplifies the logic, avoids incorrect double-calling of the .close()
callback and allows us to update error paths to simply call vma_close()
unconditionally - making VMA closure idempotent.
Link: https://lkml.kernel.org/r/28e89dda96f68c505cb6f8e9fc9b57c3e9f74b42.1730224667.git.lorenzo.stoakes@oracle.com
Fixes: deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Reported-by: Jann Horn <jannh@...gle.com>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>
Reviewed-by: Jann Horn <jannh@...gle.com>
Cc: Andreas Larsson <andreas@...sler.com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: David S. Miller <davem@...emloft.net>
Cc: Helge Deller <deller@....de>
Cc: James E.J. Bottomley <James.Bottomley@...senPartnership.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mark Brown <broonie@...nel.org>
Cc: Peter Xu <peterx@...hat.com>
Cc: Will Deacon <will@...nel.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
mm/internal.h | 7 +++++++
mm/mmap.c | 12 ++++--------
mm/nommu.c | 3 +--
mm/util.c | 15 +++++++++++++++
4 files changed, 27 insertions(+), 10 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index 85ac9c6a1393..16a4a9aece30 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -64,6 +64,13 @@ void page_writeback_init(void);
*/
int mmap_file(struct file *file, struct vm_area_struct *vma);
+/*
+ * If the VMA has a close hook then close it, and since closing it might leave
+ * it in an inconsistent state which makes the use of any hooks suspect, clear
+ * them down by installing dummy empty hooks.
+ */
+void vma_close(struct vm_area_struct *vma);
+
static inline void *folio_raw_mapping(struct folio *folio)
{
unsigned long mapping = (unsigned long)folio->mapping;
diff --git a/mm/mmap.c b/mm/mmap.c
index bf2f1ca87bef..4bfec4df51c2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -136,8 +136,7 @@ void unlink_file_vma(struct vm_area_struct *vma)
static void remove_vma(struct vm_area_struct *vma)
{
might_sleep();
- if (vma->vm_ops && vma->vm_ops->close)
- vma->vm_ops->close(vma);
+ vma_close(vma);
if (vma->vm_file)
fput(vma->vm_file);
mpol_put(vma_policy(vma));
@@ -2388,8 +2387,7 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
new->vm_start = new->vm_end;
new->vm_pgoff = 0;
/* Clean everything up if vma_adjust failed. */
- if (new->vm_ops && new->vm_ops->close)
- new->vm_ops->close(new);
+ vma_close(new);
if (new->vm_file)
fput(new->vm_file);
unlink_anon_vmas(new);
@@ -2885,8 +2883,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
return addr;
close_and_free_vma:
- if (vma->vm_ops && vma->vm_ops->close)
- vma->vm_ops->close(vma);
+ vma_close(vma);
unmap_and_free_vma:
fput(vma->vm_file);
vma->vm_file = NULL;
@@ -3376,8 +3373,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
return new_vma;
out_vma_link:
- if (new_vma->vm_ops && new_vma->vm_ops->close)
- new_vma->vm_ops->close(new_vma);
+ vma_close(new_vma);
if (new_vma->vm_file)
fput(new_vma->vm_file);
diff --git a/mm/nommu.c b/mm/nommu.c
index f09e798a4416..e0428fa57526 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -650,8 +650,7 @@ static int delete_vma_from_mm(struct vm_area_struct *vma)
*/
static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
{
- if (vma->vm_ops && vma->vm_ops->close)
- vma->vm_ops->close(vma);
+ vma_close(vma);
if (vma->vm_file)
fput(vma->vm_file);
put_nommu_region(vma->vm_region);
diff --git a/mm/util.c b/mm/util.c
index 15f1970da665..d3a2877c176f 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1121,6 +1121,21 @@ int mmap_file(struct file *file, struct vm_area_struct *vma)
return err;
}
+void vma_close(struct vm_area_struct *vma)
+{
+ static const struct vm_operations_struct dummy_vm_ops = {};
+
+ if (vma->vm_ops && vma->vm_ops->close) {
+ vma->vm_ops->close(vma);
+
+ /*
+ * The mapping is in an inconsistent state, and no further hooks
+ * may be invoked upon it.
+ */
+ vma->vm_ops = &dummy_vm_ops;
+ }
+}
+
#ifdef CONFIG_PRINTK
/**
* mem_dump_obj - Print available provenance information
--
2.47.0
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