Commit 8dcf757d authored Nov 15, 2024 by Lorenzo Stoakes Committed by Wen Zhiwei Jan 15, 2025

mm: unconditionally close VMAs on error

stable inclusion
from stable-v6.6.63
commit a97fe6889b25648b7d990d83bf63b2f0e1f1c545
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IBI1RP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a97fe6889b25648b7d990d83bf63b2f0e1f1c545

--------------------------------

[ 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: deb0f656 ("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>
Signed-off-by: Wen Zhiwei <wenzhiwei@kylinos.cn>

parent a163c319

mm/internal.h

+18 −0

Original line number	Diff line number	Diff line
		@@ -287,6 +287,24 @@ static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, pte_t pte)
		}
		#endif /* CONFIG_MMU */

		/*
		* 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)

mm/mmap.c

+3 −6

Original line number	Diff line number	Diff line
		@@ -179,8 +179,7 @@ void unlink_file_vma_batch_final(struct unlink_vma_file_batch *vb)
		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));
		@@ -2963,8 +2962,7 @@ static unsigned long __mmap_region(struct mm_struct *mm,
		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:
		@@ -3504,8 +3502,7 @@ 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);

mm/nommu.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -598,8 +598,7 @@ 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);