On Sat, 09 Jul 2016 15:58:20 +1000, Michael Ellerman said: > I then get two hits, which may or may not be valid: > > [ 2.309556] usercopy: kernel memory overwrite attempt detected to d000000003510028 (kernfs_node_cache) (64 bytes) > [ 2.309995] CPU: 7 PID: 2241 Comm: wait-for-root Not tainted 4.7.0-rc3-00099-g97872fc89d41 #64 > [ 2.310480] Call Trace: > [ 2.310556] [c0000001f4773bf0] [c0000000009bdbe8] dump_stack+0xb0/0xf0 (unreliable) > [ 2.311016] [c0000001f4773c30] [c00000000029cf44] __check_object_size+0x74/0x320 > [ 2.311472] [c0000001f4773cb0] [c00000000005d4d0] copy_from_user+0x60/0xd4 > [ 2.311873] [c0000001f4773cf0] [c0000000008b38f4] __get_filter+0x74/0x160 > [ 2.312230] [c0000001f4773d30] [c0000000008b408c] sk_attach_filter+0x2c/0xc0 > [ 2.312596] [c0000001f4773d60] [c000000000871c34] sock_setsockopt+0x954/0xc00 > [ 2.313021] [c0000001f4773dd0] [c00000000086ac44] SyS_setsockopt+0x134/0x150 > [ 2.313380] [c0000001f4773e30] [c000000000009260] system_call+0x38/0x108 Yeah, 'ping' dies with a similar traceback going to rawv6_setsockopt(), and 'trinity' dies a horrid death during initialization because it creates some sctp sockets to fool around with. The problem in all these cases is that setsockopt uses copy_from_user() to pull in the option value, and the allocation isn't tagged with USERCOPY to whitelist it. Unfortunately, I haven't been able to track down where in net/ the memory is allocated, nor is there any good hint in the grsecurity patch that I can find where they do the tagging. And the fact that so far, I'm only had ping and trinity killed in setsockopt() hints that *most* setsockopt() calls must be going through a code path that does allocate suitable memory, and these two have different paths. I can't believe they're the only two binaries that call setsockopt()..... Just saw your second mail, now I'm wondering why *my* laptop doesn't die a horrid death when systemd starts up. Mine is systemd-230-3.gitea68351.fc25.x86_64 - maybe there's something release-dependent going on?
Attachment:
pgpz7MuYpZNpu.pgp
Description: PGP signature
