FROMGIT: tcp: enforce tcp_min_snd_mss in tcp_mtu_probing()

commit 967c05aee439e6e5d7d805e195b3a20ef5c433d6 upstream.

If mtu probing is enabled tcp_mtu_probing() could very well end up
with a too small MSS.

Use the new sysctl tcp_min_snd_mss to make sure MSS search
is performed in an acceptable range.

CVE-2019-11479 -- tcp mss hardcoded to 48

Signed-off-by: Eric Dumazet <>
Reported-by: Jonathan Lemon <>
Cc: Jonathan Looney <>
Acked-by: Neal Cardwell <>
Cc: Yuchung Cheng <>
Cc: Tyler Hicks <>
Cc: Bruce Curtis <>
Signed-off-by: David S. Miller <>
Signed-off-by: Greg Kroah-Hartman <>
(cherry picked from commit 59222807fcc99951dc769cd50e132e319d73d699
 git:// linux-4.19.y)
Signed-off-by: Robert Kolchmeyer <>

TEST=build and run

Change-Id: I6c04a5c64dc3e79733c646cb47d736a3a19af95c
Reviewed-by: Sean Paul <>
Reviewed-by: Guenter Roeck <>
Tested-by: Robert Kolchmeyer <>
1 file changed