6.11-stable review patch. If anyone has any objections, please let me know.
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From: Wei Yang richard.weiyang@gmail.com
commit faa242b1d2a97143150bdc50d5b61fd70fcd17cd upstream.
After commit 94d7d9233951 ("mm: abstract the vma_merge()/split_vma() pattern for mprotect() et al."), if vma_modify_flags() return error, the vma is set to an error code. This will lead to an invalid prev be returned.
Generally this shouldn't matter as the caller should treat an error as indicating state is now invalidated, however unfortunately apply_mlockall_flags() does not check for errors and assumes that mlock_fixup() correctly maintains prev even if an error were to occur.
This patch fixes that assumption.
[lorenzo.stoakes@oracle.com: provide a better fix and rephrase the log] Link: https://lkml.kernel.org/r/20241027123321.19511-1-richard.weiyang@gmail.com Fixes: 94d7d9233951 ("mm: abstract the vma_merge()/split_vma() pattern for mprotect() et al.") Signed-off-by: Wei Yang richard.weiyang@gmail.com Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Liam R. Howlett Liam.Howlett@Oracle.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Jann Horn jannh@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/mlock.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/mm/mlock.c b/mm/mlock.c index e3e3dc2b2956..cde076fa7d5e 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -725,14 +725,17 @@ static int apply_mlockall_flags(int flags) }
for_each_vma(vmi, vma) { + int error; vm_flags_t newflags;
newflags = vma->vm_flags & ~VM_LOCKED_MASK; newflags |= to_add;
- /* Ignore errors */ - mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end, - newflags); + error = mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end, + newflags); + /* Ignore errors, but prev needs fixing up. */ + if (error) + prev = vma; cond_resched(); } out: