4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jann Horn jannh@google.com
[ Upstream commit dffd22aed2aa1e804bccf19b30a421e89ee2ae61 ]
When proc_dostring() is called with a non-zero offset in strict mode, it doesn't just write to the ->data buffer, it also reads. Make sure it doesn't read uninitialized data.
Fixes: c6ac37d8d884 ("netfilter: nf_log: fix error on write NONE to [...]") Signed-off-by: Jann Horn jannh@google.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_log.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/net/netfilter/nf_log.c +++ b/net/netfilter/nf_log.c @@ -440,6 +440,10 @@ static int nf_log_proc_dostring(struct c if (write) { struct ctl_table tmp = *table;
+ /* proc_dostring() can append to existing strings, so we need to + * initialize it as an empty string. + */ + buf[0] = '\0'; tmp.data = buf; r = proc_dostring(&tmp, write, buffer, lenp, ppos); if (r)