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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: deb0f65628 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reported-by: Jann Horn <jannh@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Jann Horn <jannh@google.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lorenzo Stoakes 2024-11-15 12:41:55 +00:00 committed by Greg Kroah-Hartman
parent cd3ed99fca
commit a97fe6889b
3 changed files with 22 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
mm/internal.h
View File

@ -110,6 +110,24 @@ static inline int mmap_file(struct file *file, struct vm_area_struct *vma)
return err;
}
/*
* 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.
*/
static inline void vma_close(struct vm_area_struct *vma)
{
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 = &vma_dummy_vm_ops;
}
}
void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio,
int nr_throttled);
static inline void acct_reclaim_writeback(struct folio *folio)

9
mm/mmap.c
View File

@ -137,8 +137,7 @@ void unlink_file_vma(struct vm_area_struct *vma)
static void remove_vma(struct vm_area_struct *vma, bool unreachable)
{
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));
@ -2899,8 +2898,7 @@ expanded:
return addr;
close_and_free_vma:
if (file && vma->vm_ops && vma->vm_ops->close)
vma->vm_ops->close(vma);
vma_close(vma);
if (file || vma->vm_file) {
unmap_and_free_vma:
@ -3392,8 +3390,7 @@ 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);

3
mm/nommu.c
View File

@ -600,8 +600,7 @@ 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);