In order to learn the jprobes interface, I am a writing a fairly silly example
jprobe. However, I'm having issues copying a string from userspace....
Basically somehow I wind up calling a function that may sleep from an invalid
context (interrupts disabled or something).
I have the source of the function in question and the stack trace below. If
anyone could give me a few pointers it would be greatly appreciated.
The function in question is:
(> 74 asmlinkage static int j_sys_open(const char __user * filename, int flags,
int mode)
75 {
0> 76 char tmp[1024];
.> 77
78 strncpy_from_user(tmp, filename, 1024);
79 // char * tmp = getname(filename);
80 // int fd = PTR_ERR(tmp);
81
82 if (!IS_ERR(tmp))
83 {
84 if (strstr(tmp, ".exe"))
85 {
86
87 if (strcmp(current->comm, "wine"))
88 {
89 goto out;
90 }
91
92 panic("PANIC: The file %s is virus infected. Self destruction
imminent.\n", tmp);
93
94 }
95 }
96
97 out:
98 jprobe_return();
99 return 0;
100 }
and the error in dmesg is:
[ 421.250737] BUG: sleeping function called from invalid context at
arch/x86/mm/fault.c:1074
[ 421.250742] in_atomic(): 0, irqs_disabled(): 1, pid: 1718, name: dmesg
[ 421.250745] Pid: 1718, comm: dmesg Not tainted 2.6.35.9-64.fc14.x86_64 #1
[ 421.250748] Call Trace:
[ 421.250756] [<ffffffff8103d1d5>] __might_sleep+0xeb/0xf0
[ 421.250761] [<ffffffff8146cbf4>] do_page_fault+0x15c/0x265
[ 421.250765] [<ffffffff8146a075>] page_fault+0x25/0x30
[ 421.250770] [<ffffffff8121db83>] ? strncpy+0xc/0x27
[ 421.250774] [<ffffffffa000f049>] j_sys_open+0x37/0xc6 [exe_probe]
[ 421.250779] [<ffffffff810e6fa5>] ? zone_statistics+0x65/0x6a
[ 421.250784] [<ffffffff810d996b>] ? get_page_from_freelist+0x4c7/0x674
[ 421.250787] [<ffffffff810e6fa5>] ? zone_statistics+0x65/0x6a
[ 421.250791] [<ffffffff810d996b>] ? get_page_from_freelist+0x4c7/0x674
[ 421.250795] [<ffffffff81111cd8>] ? try_get_mem_cgroup_from_mm+0x33/0x3f
[ 421.250798] [<ffffffff81112709>] ? __mem_cgroup_try_charge+0x70/0x3bc
[ 421.250802] [<ffffffff8103c0ea>] ? need_resched+0x23/0x2d
[ 421.250806] [<ffffffff8103c102>] ? should_resched+0xe/0x2e
[ 421.250809] [<ffffffff81468375>] ? _cond_resched+0xe/0x22
[ 421.250812] [<ffffffff810d3672>] ? lock_page+0x31/0x42
[ 421.250815] [<ffffffff810d4185>] ? filemap_fault+0x1bb/0x30a
[ 421.250818] [<ffffffff810d3796>] ? unlock_page+0x27/0x2c
[ 421.250822] [<ffffffff810e9c16>] ? __do_fault+0x342/0x379
[ 421.250826] [<ffffffff810e929d>] ? pmd_offset+0x19/0x40
[ 421.250829] [<ffffffff810ebe02>] ? handle_mm_fault+0x3a9/0x84d
[ 421.250832] [<ffffffff810ef344>] ? remove_vma+0x7f/0x87
[ 421.250836] [<ffffffff8146ccd0>] ? do_page_fault+0x238/0x265
[ 421.250840] [<ffffffff81099961>] ? audit_syscall_entry+0x11c/0x148
[ 421.250844] [<ffffffff81009cf2>] system_call_fastpath+0x16/0x1b
Regards,
Greg Kerr
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