From: NeilBrown <neilb@xxxxxxx>
Subject: x86: fix seq_file iteration for pat/memtype.c
The memtype seq_file iterator allocates a buffer in the ->start and ->next
functions and frees it in the ->show function. The preferred handling for
such resources is to free them in the subsequent ->next or ->stop function
call.
Since Commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration
code and interface") there is no guarantee that ->show will be called
after ->next, so this function can now leak memory.
So move the freeing of the buffer to ->next and ->stop.
Link: https://lkml.kernel.org/r/161248539022.21478.13874455485854739066.stgit@noble1
Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface")
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Cc: Xin Long <lucien.xin@xxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Vlad Yasevich <vyasevich@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/pat/memtype.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/mm/pat/memtype.c~x86-fix-seq_file-iteration-for-pat-memtypec
+++ a/arch/x86/mm/pat/memtype.c
@@ -1164,12 +1164,14 @@ static void *memtype_seq_start(struct se
static void *memtype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
+ kfree(v);
++*pos;
return memtype_get_idx(*pos);
}
static void memtype_seq_stop(struct seq_file *seq, void *v)
{
+ kfree(v);
}
static int memtype_seq_show(struct seq_file *seq, void *v)
@@ -1181,8 +1183,6 @@ static int memtype_seq_show(struct seq_f
entry_print->end,
cattr_name(entry_print->type));
- kfree(entry_print);
-
return 0;
}
_
