This is a patch (& bug report) for a crash in sysctl_set_parent()
in 2.6.22-git2.
Problem: 2.6.22-git2 crashes with a stack trace
[c000000001d0fb00] c000000000067b4c .sysctl_set_parent+0x48/0x7c
[c000000001d0fb90] c000000000069b40 .register_sysctl_table+0x7c/0xf4
[c000000001d0fc30] c00000000065e710 .devinet_init+0x88/0xb0
[c000000001d0fcc0] c00000000065db74 .ip_rt_init+0x17c/0x32c
[c000000001d0fd70] c00000000065deec .ip_init+0x10/0x34
[c000000001d0fdf0] c00000000065e898 .inet_init+0x160/0x3dc
[c000000001d0fea0] c000000000630bc4 .kernel_init+0x204/0x3c8
A bit of poking around makes it clear what the problem is:
In sysctl_set_parent(), the for loop
for (; table->ctl_name || table->procname; table++) {
walks off the end of the table, and into garbage. Basically,
this for-loop iterator expects all table arrays to be
"null terminated". However, net/ipv4/devinet.c statically
declares an array that is not null-terminated. The patch
below fixes that; it works for me. Its somewhat conservative;
if one wishes to assume that the compiler will always zero out
the empty parts of the structure, then this pach can be shrunk
to one line: + ctl_table devinet_root_dir[3];
Signed-off-by: Linas Vepstas <[email protected]>
----
I tried to audit some of the code to see where else there
might be similar badly-formed static declarations. This is hard,
as there's a lot of code. Most seems fine.
net/core/neighbour.c | 4 ++++
net/ipv4/devinet.c | 7 ++++++-
2 files changed, 10 insertions(+), 1 deletion(-)
Index: linux-2.6.22-git2/net/ipv4/devinet.c
===================================================================
--- linux-2.6.22-git2.orig/net/ipv4/devinet.c 2007-07-13 14:23:21.000000000 -0500
+++ linux-2.6.22-git2/net/ipv4/devinet.c 2007-07-13 14:24:15.000000000 -0500
@@ -1424,7 +1424,7 @@ static struct devinet_sysctl_table {
ctl_table devinet_dev[2];
ctl_table devinet_conf_dir[2];
ctl_table devinet_proto_dir[2];
- ctl_table devinet_root_dir[2];
+ ctl_table devinet_root_dir[3];
} devinet_sysctl = {
.devinet_vars = {
DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
@@ -1493,8 +1493,13 @@ static struct devinet_sysctl_table {
.data = &ipv4_devconf.loop,
.maxlen = sizeof(int),
.mode = 0644,
+ .child = 0x0,
.proc_handler = &proc_dointvec,
},
+ {
+ .ctl_name = 0,
+ .procname = 0,
+ },
},
};
-
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