From 61dc9f776705d6db6847c101b98fa4f0e9eb6fa3 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 10 Feb 2026 11:27:38 -0800 Subject: [PATCH] procfs: fix possible double mmput() in do_procmap_query() When user provides incorrectly sized buffer for build ID for PROCMAP_QUERY we return with -ENAMETOOLONG error. After recent changes this condition happens later, after we unlocked mmap_lock/per-VMA lock and did mmput(), so original goto out is now wrong and will double-mmput() mm_struct. Fix by jumping further to clean up only vm_file and name_buf. Link: https://lkml.kernel.org/r/20260210192738.3041609-1-andrii@kernel.org Fixes: b5cbacd7f86f ("procfs: avoid fetching build ID while holding VMA lock") Signed-off-by: Andrii Nakryiko Reported-by: Ruikai Peng Reported-by: Thomas Gleixner Tested-by: Thomas Gleixner Reviewed-by: Shakeel Butt Reported-by: syzbot+237b5b985b78c1da9600@syzkaller.appspotmail.com Cc: Ruikai Peng Closes: https://lkml.kernel.org/r/CAFD3drOJANTZPuyiqMdqpiRwOKnHwv5QgMNZghCDr-WxdiHvMg@mail.gmail.com Closes: https://lore.kernel.org/all/698aaf3c.050a0220.3b3015.0088.GAE@google.com/T/#u Cc: Signed-off-by: Andrew Morton --- fs/proc/task_mmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 26188a4ad1abd..2f55efc368162 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -780,7 +780,7 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg) } else { if (karg.build_id_size < build_id_sz) { err = -ENAMETOOLONG; - goto out; + goto out_file; } karg.build_id_size = build_id_sz; } @@ -808,6 +808,7 @@ static int do_procmap_query(struct mm_struct *mm, void __user *uarg) out: query_vma_teardown(&lock_ctx); mmput(mm); +out_file: if (vm_file) fput(vm_file); kfree(name_buf); -- 2.47.3