Messages in this thread | | | Date | Tue, 11 Jul 2023 09:05:15 +0900 | From | Masami Hiramatsu (Google) <> | Subject | Re: [PATCH v3 4/4] tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails |
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On Mon, 10 Jul 2023 18:16:01 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Sat, 8 Jul 2023 11:48:58 +0900 > "Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote: > > > --- a/kernel/trace/trace_probe_kernel.h > > +++ b/kernel/trace/trace_probe_kernel.h > > @@ -55,8 +55,7 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base) > > __dest = get_loc_data(dest, base); > > > > ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); > > - if (ret >= 0) > > - *(u32 *)dest = make_data_loc(ret, __dest - base); > > + *(u32 *)dest = make_data_loc((ret >= 0) ? ret : 0, __dest - base); > > > > return ret; > > } > > @@ -87,8 +86,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) > > * probing. > > */ > > ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); > > - if (ret >= 0) > > - *(u32 *)dest = make_data_loc(ret, __dest - base); > > + *(u32 *)dest = make_data_loc((ret >= 0) ? ret : 0, __dest - base); > > The above is a complex line, and not something that I think should be cut > and pasted between two different locations. > > I know you took out the set_data_loc() helper, but really it should have > stayed, and have used that to update this code in the two places it > affected, instead of making the changes in those two locations. > > That is, patch 3 could have had kept. > > static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base) > { > if (ret >= 0) > *(u32 *)dest = make_data_loc(ret, __dest - base); > }
To avoid confusion, I would like to revert the set_data_loc() at the 3rd patch and add it again in 4th patch.
> > And this patch could have been: > > static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base) > { > *(u32 *)dest = make_data_loc(ret, __dest - base); > }
and introduce it. I also want to put the ternary operator into set_data_loc() too for simplicity.
static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base) { if (ret < 0) ret = 0; *(u32 *)dest = make_data_loc(ret, __dest - base); }
Thanks,
> > That would keep the complexity down in this changes set. > > -- Steve > > > > > > return ret; > > }
-- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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