Previous patch ("VFS: simplify seq_file iteration code and interface")
removed code to set ->from to zero when ->count is zero, as ->from is
dead at that time. However it didn't ensure ->from was set properly
whenever ->count becomes non-zero.
This can only happen when ->show() is called. Of the three places it
is called one already has ->from set to zero. The other two are
fixed by setting from to zero after fully flushing the buffer (at which
point ->count will also be zero).
Reported-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
fs/seq_file.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index fd82585ab50f..1dea7a8a5255 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -220,6 +220,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
goto Done;
}
/* we need at least one record in buffer */
+ m->from = 0;
p = m->op->start(m, &m->index);
while (1) {
err = PTR_ERR(p);
--
2.14.0.rc0.dirty
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