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mm: unconditionally close VMAs on error

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[ Upstream commit 4080ef1579 ]

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 12:38:14 +00:00 committed by Greg Kroah-Hartman
parent 105d04c88e
commit a08241812f
4 changed files with 26 additions and 8 deletions
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7
mm/internal.h
View File

@ -46,6 +46,13 @@ 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);
vm_fault_t do_swap_page(struct vm_fault *vmf);
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,

9
mm/mmap.c
View File

@ -180,8 +180,7 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
struct vm_area_struct *next = vma->vm_next;
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));
@ -1877,8 +1876,7 @@ out:
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;
@ -2762,8 +2760,7 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
return 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);

3
mm/nommu.c
View File

@ -652,8 +652,7 @@ static void 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);

15
mm/util.c
View File

@ -1104,6 +1104,21 @@ 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