https://bugs.kde.org/show_bug.cgi?id=364413
Bug ID: 364413
Summary: pselect sycallwrapper mishandles NULL sigmask
Product: valgrind
Version: 3.11 SVN
Platform: Other
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1344082
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: m...@redhat.com
This is a regression caused by valgrind svn r15823 which fixed Bug 359871
"sanitize signal mask in ppoll and pselect syscalls".
The issue is caused by this C library/kernel ABI differences according to
http://man7.org/linux/man-pages/man2/pselect6.2.html
The Linux pselect6() system call modifies its timeout argument.
However, the glibc wrapper function hides this behavior by using a
local variable for the timeout argument that is passed to the system
call. Thus, the glibc pselect() function does not modify its timeout
argument; this is the behavior required by POSIX.1-2001.
The final argument of the pselect6() system call is not a sigset_t *
pointer, but is instead a structure of the form:
struct {
const sigset_t *ss; /* Pointer to signal set */
size_t ss_len; /* Size (in bytes) of object pointed
to by 'ss' */
};
This allows the system call to obtain both a pointer to the signal
set and its size, while allowing for the fact that most architectures
support a maximum of 6 arguments to a system call.
What we are seeing is glibc modifying the timeout argument (NULL) and passing
it as a struct { NULL, 8 } (where 8 is the correct ss_len if ss wouldn't be
NULL).
valgrind doesn't check whether ss is NULL before calling PRE_MEM_READ on it and
so generates a bogus warning.
Reproducible: Always
--
You are receiving this mail because:
You are watching all bug changes.
