Hi Mikołaj, On Wed, Aug 07, 2024 at 12:07:57AM GMT, Mikołaj Kołek wrote: > This patch clears up the wording of the first part of the BUGS section > of the sigaction.2 man page. > Currently, it is very unclear when exactly the bug can occur, and > there is no example, which I aim to fix. > > I also attach the source code of a C program that, Please include the example program in the commit message. > when run on an x86 > Linux computer, shows that my example behaves like I say it does. The > code runs the int instruction for each value from 0 to 255 with all > registers set to 0 to show what is contained in the siginfo_t returned > to the signal handler afterwards. > > The program is based on the attachment to bug 205831 on the kernel > Bugzilla, which first dealt with this issue, you can find that bug > report here: https://bugzilla.kernel.org/show_bug.cgi?id=205831. The > text of my contribution is also partially based on the BUGS section of > the signal.2 man page. Please CC the people that contributed in that discussion. Have a lovely night! Alex > > Signed-off-by: Mikołaj Kołek <kolek.mikolaj@xxxxxxxxx> > --- > man/man2/sigaction.2 | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/man/man2/sigaction.2 b/man/man2/sigaction.2 > index df8826e71..2b797355b 100644 > --- a/man/man2/sigaction.2 > +++ b/man/man2/sigaction.2 > @@ -1129,13 +1129,29 @@ .SS Undocumented > See the relevant Linux kernel sources for details. > This use is obsolete now. > .SH BUGS > -When delivering a signal with a > +When delivering a signal resulting from a hardware exception with a > .B SA_SIGINFO > handler, > the kernel does not always provide meaningful values > for all of the fields of the > .I siginfo_t > that are relevant for that signal. > +For example, when the x86 > +.I int > +instruction is called with a forbidden argument > +(any number other than 3 or 128), a > +.BR SIGSEGV > +signal is delivered, but the > +.I siginfo_t > +passed to the signal handler has all its fields besides > +.I si_signo > +and > +.I si_code > +set to zero, even if other fields should be set (as an example, > +.I si_addr > +should be non-zero for all > +.BR SIGSEGV > +signals). > .P > Up to and including Linux 2.6.13, specifying > .B SA_NODEFER > -- > 2.46.0 -- <https://www.alejandro-colomar.es/>
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