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author | Eric Biggers <ebiggers@google.com> | 2018-04-17 00:29:22 +0300 |
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committer | David S. Miller <davem@davemloft.net> | 2018-04-17 20:42:58 +0300 |
commit | c210f7b411790ee0fc4252547d645c5d8648adc5 (patch) | |
tree | 965500d01e87df8c69c28e582efa98e2958013bf /net/ncsi/internal.h | |
parent | e3c1917e45d030411888285f56c9d42e7472cb1f (diff) | |
download | linux-c210f7b411790ee0fc4252547d645c5d8648adc5.tar.xz |
KEYS: DNS: limit the length of option strings
Adding a dns_resolver key whose payload contains a very long option name
resulted in that string being printed in full. This hit the WARN_ONCE()
in set_precision() during the printk(), because printk() only supports a
precision of up to 32767 bytes:
precision 1000000 too large
WARNING: CPU: 0 PID: 752 at lib/vsprintf.c:2189 vsnprintf+0x4bc/0x5b0
Fix it by limiting option strings (combined name + value) to a much more
reasonable 128 bytes. The exact limit is arbitrary, but currently the
only recognized option is formatted as "dnserror=%lu" which fits well
within this limit.
Also ratelimit the printks.
Reproducer:
perl -e 'print "#", "A" x 1000000, "\x00"' | keyctl padd dns_resolver desc @s
This bug was found using syzkaller.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 4a2d789267e0 ("DNS: If the DNS server returns an error, allow that to be cached [ver #2]")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ncsi/internal.h')
0 files changed, 0 insertions, 0 deletions