[PATCH] proc: use untagged_addr() for pagemap_read addresses
From: Miles Chen <hidden>
Date: 2020-08-03 15:40:02
Also in:
linux-fsdevel, linux-mediatek, lkml
Subsystem:
filesystems (vfs and infrastructure), memory mapping, proc filesystem, the rest · Maintainers:
Alexander Viro, Christian Brauner, Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds
When we try to visit the pagemap of a tagged userspace pointer, we find that the start_vaddr is not correct because of the tag. To fix it, we should untag the usespace pointers in pagemap_read(). Signed-off-by: Miles Chen <redacted> --- fs/proc/task_mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index dbda4499a859..d0c6e8e0cf37 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c@@ -1541,11 +1541,11 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, src = *ppos; svpfn = src / PM_ENTRY_BYTES; - start_vaddr = svpfn << PAGE_SHIFT; + start_vaddr = untagged_addr(svpfn << PAGE_SHIFT); end_vaddr = mm->task_size; /* watch out for wraparound */ - if (svpfn > mm->task_size >> PAGE_SHIFT) + if (start_vaddr > mm->task_size) start_vaddr = end_vaddr; /*
--
2.18.0
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