Messages in this thread Patch in this message | | | From | Rasmus Villemoes <> | Subject | Re: [PATCH v3 3/3] lib/string_helpers.c: Change semantics of string_escape_mem | Date | Mon, 23 Feb 2015 23:55:51 +0100 |
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On Mon, Feb 23 2015, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
>> >> > So, why couldn't we split this to separate test case? It seems I already >> >> > pointed this out. >> >> > >> >> >> >> This actually provides better coverage >> > >> > I do not see much advantage of doing so. You may create a loop with >> > random number for in-size and check. So, I prefer to see separate case >> > for that. >> >> It's not about the size, it's about exercising all the various escape_* >> helpers, to ensure that they all respect the end of the buffer, while >> still returning the correct would-be output size. For that, one needs to >> call string_escape_mem with various combinations of flags and input >> buffers. The logic for that is already in place in test_string_escape >> and its caller, and I see no point in duplicating all that. > > Thanks for clarification. > >> If you insist on a separate function for doing the overflow testing, >> I'll just rip it out from my code and let you add such a test later. > > What about to make it a separate function *and* call from inside of > test_string_escape? Would it work for you?
See my earlier point about "quite a lot of state to pass". But if this
static __init void test_string_escape_overflow(const char *in, int p, char *out_real, int out_size, unsigned int flags, const char *esc, int q_test, const char *name) { int q_real;
memset(out_real, 'Z', out_size); q_real = string_escape_mem(in, p, out_real, 0, flags, esc); if (q_real != q_test) pr_warn("Test '%s' failed: flags = %u, osz = 0, expected %d, got %d\n", name, flags, q_test, q_real); if (memchr_inv(out_real, 'Z', out_size)) pr_warn("Test '%s' failed: osz = 0 but string_escape_mem wrote to the buffer\n", name); }
is what you want, sure, have it your way.
I need to fix fs/proc/array.c in 3/3 as well, to make the kernel compile+boot and make the series bisectable. Before I send v4 please let me know what you think about this (the minimal fix I could come up with):
diff --git a/fs/proc/array.c b/fs/proc/array.c index 1295a00ca316..20f2d50e2dba 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -99,10 +99,9 @@ static inline void task_name(struct seq_file *m, struct task_struct *p) buf = m->buf + m->count; /* Ignore error for now */ - string_escape_str(tcomm, &buf, m->size - m->count, - ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\"); + m->count += string_escape_str(tcomm, buf, m->size - m->count, + ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\"); - m->count = buf - m->buf; seq_putc(m, '\n'); } [Longer-term I think it would be a lot better not to poke around in the internals of struct seq_file. One way is to do the escaping into a stack buffer (2*sizeof(p->comm) should be enough) and then use something like seq_write(m, buffer, min(sizeof(buffer), return-value-from-string_escape_str)). Another option is to do everything with a single seq_printf call, something like
seq_printf(m, "Name:\t%*pEcs\n, (int)strlen(tcomm), tcomm)
That will escape more than just \ and \n, but that would IMO be an improvement. But of course this is out of scope for this series.]
Rasmus
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