From f3bffde4a8106d3a538560dc6855d25fc5d51b86 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Wed, 26 Feb 2025 22:49:14 +0900 Subject: [PATCH] mm/mlock: set the correct prev on failure BugLink: https://bugs.launchpad.net/bugs/2100292 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 Reviewed-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Cc: Vlastimil Babka Cc: Jann Horn Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman Signed-off-by: Koichiro Den Signed-off-by: Stefan Bader --- mm/mlock.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/mlock.c b/mm/mlock.c index 086546ac5766..052b4a7e1678 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -737,14 +737,17 @@ 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: