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netfilter: nf_log: fix uninit read in nf_log_proc_dostring

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[ 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: c6ac37d8d8 ("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>
This commit is contained in:
Jann Horn 2018-06-20 18:33:45 +02:00 • committed by Greg Kroah-Hartman
parent 1ea053d1cc
commit 4c3b0ae79f
1 changed files with 4 additions and 0 deletions
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4
net/netfilter/nf_log.c
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@ -440,6 +440,10 @@ static int nf_log_proc_dostring(struct ctl_table *table, int write,
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)