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author | cem <cem@FreeBSD.org> | 2015-10-06 18:07:00 +0000 |
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committer | cem <cem@FreeBSD.org> | 2015-10-06 18:07:00 +0000 |
commit | 9c1e214f79cb8f8fb38ba2f8fa010f282ec5be79 (patch) | |
tree | 9844297e32023403c9df2beefdd3462b21290b04 /sys/kern/kern_exec.c | |
parent | a6f4f28b545e1f0632ba4b20b86a7ab487932373 (diff) | |
download | FreeBSD-src-9c1e214f79cb8f8fb38ba2f8fa010f282ec5be79.zip FreeBSD-src-9c1e214f79cb8f8fb38ba2f8fa010f282ec5be79.tar.gz |
Fix core corruption caused by race in note_procstat_vmmap
This fix is spiritually similar to r287442 and was discovered thanks to
the KASSERT added in that revision.
NT_PROCSTAT_VMMAP output length, when packing kinfo structs, is tied to
the length of filenames corresponding to vnodes in the process' vm map
via vn_fullpath. As vnodes may move during coredump, this is racy.
We do not remove the race, only prevent it from causing coredump
corruption.
- Add a sysctl, kern.coredump_pack_vmmapinfo, to allow users to disable
kinfo packing for PROCSTAT_VMMAP notes. This avoids VMMAP corruption
and truncation, even if names change, at the cost of up to PATH_MAX
bytes per mapped object. The new sysctl is documented in core.5.
- Fix note_procstat_vmmap to self-limit in the second pass. This
addresses corruption, at the cost of sometimes producing a truncated
result.
- Fix PROCSTAT_VMMAP consumers libutil (and libprocstat, via copy-paste)
to grok the new zero padding.
Reported by: pho (https://people.freebsd.org/~pho/stress/log/datamove4-2.txt)
Relnotes: yes
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D3824
Diffstat (limited to 'sys/kern/kern_exec.c')
-rw-r--r-- | sys/kern/kern_exec.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c index fb78adf..a0eb069 100644 --- a/sys/kern/kern_exec.c +++ b/sys/kern/kern_exec.c @@ -105,6 +105,11 @@ SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN, &coredump_pack_fileinfo, 0, "Enable file path packing in 'procstat -f' coredump notes"); +int coredump_pack_vmmapinfo = 1; +SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN, + &coredump_pack_vmmapinfo, 0, + "Enable file path packing in 'procstat -v' coredump notes"); + static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS); static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS); static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS); |