Commit 61dc9f77 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Andrew Morton
Browse files

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: b5cbacd7 ("procfs: avoid fetching build ID while holding VMA lock")
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Reported-by: default avatarRuikai Peng <ruikai@pwno.io>
Reported-by: default avatarThomas Gleixner <tglx@kernel.org>
Tested-by: default avatarThomas Gleixner <tglx@kernel.org>
Reviewed-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Reported-by: default avatar <syzbot+237b5b985b78c1da9600@syzkaller.appspotmail.com>
Cc: Ruikai Peng <ruikai@pwno.io>
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: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 338ad1e8

fs/proc/task_mmu.c

+2 −1
Original line number Diff line number Diff line
@@ -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);