Messages in this thread | | | Subject | Re: [PATCH v2 2/3] vsprintf: print <no-symbol> if symbol not found | From | Joe Perches <> | Date | Mon, 18 Dec 2017 22:18:27 -0800 |
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On Tue, 2017-12-19 at 14:28 +1100, Tobin C. Harding wrote: > Depends on: commit 40eee173a35e ("kallsyms: don't leak address when > symbol not found") > > Currently vsprintf for specifiers %p[SsB] relies on the behaviour of > kallsyms (sprint_symbol()) and prints the actual address if a symbol is > not found. Previous patch changes this behaviour so that sprint_symbol() > returns an error if symbol not found. With this patch in place we can > print a sanitized message '<symbol not found>' instead of leaking the > address. > > Print '<symbol not found>' for printk specifier %p[sSB] if symbol look > up fails. > > Signed-off-by: Tobin C. Harding <me@tobin.cc> > --- > lib/vsprintf.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index 01c3957b2de6..820ed4fe6e6c 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -674,6 +674,8 @@ char *symbol_string(char *buf, char *end, void *ptr, > unsigned long value; > #ifdef CONFIG_KALLSYMS > char sym[KSYM_SYMBOL_LEN]; > + const char *sym_not_found = "<symbol not found>";
This will be reinitialized on every use.
> + int ret; > #endif > > if (fmt[1] == 'R') > @@ -682,11 +684,14 @@ char *symbol_string(char *buf, char *end, void *ptr, > > #ifdef CONFIG_KALLSYMS > if (*fmt == 'B') > - sprint_backtrace(sym, value); > + ret = sprint_backtrace(sym, value); > else if (*fmt != 'f' && *fmt != 's') > - sprint_symbol(sym, value); > + ret = sprint_symbol(sym, value); > else > - sprint_symbol_no_offset(sym, value); > + ret = sprint_symbol_no_offset(sym, value); > + > + if (ret == -1) > + strcpy(sym, sym_not_found);
This could avoid the unnecessary strcpy if sym_not_found was not used at all and this was used instead
if (ret == -1) return string(buf, end, "<symbol not found>", spec);
return string(buf, end, sym, spec);
or maybe
return string(buf, end, ret == -1 ? "<symbol not found>" : sum, spec);
> > return string(buf, end, sym, spec); > #else
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