https://bugs.kde.org/show_bug.cgi?id=422623
Bug ID: 422623
Summary: epoll_ctl triggers valgrind warnings on aarch64
Product: valgrind
Version: unspecified
Platform: Other
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1844778
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: jsew...@acm.org
Reporter: m...@klomp.org
Target Milestone: ---
We check the event param with:
PRE_MEM_READ( "epoll_ctl(event)", ARG4, sizeof(struct vki_epoll_event) );
But struct vki_epoll_event is defined as:
#ifdef __x86_64__
#define VKI_EPOLL_PACKED __attribute__((packed))
#else
#define VKI_EPOLL_PACKED
#endif
struct vki_epoll_event {
__vki_u32 events;
__vki_u64 data;
} VKI_EPOLL_PACKED;
Which mimics the kernel headers and means it isn't packed on non-x86_64 arches
and might contain padding on such architectures (as it does on arm64).
This can be solved with something like the following:
diff --git a/coregrind/m_syswrap/syswrap-linux.c
b/coregrind/m_syswrap/syswrap-l
index f1ecbbf..e94c448 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -1923,8 +1923,13 @@ PRE(sys_epoll_ctl)
SARG1, ( ARG2<3 ? epoll_ctl_s[ARG2] : "?" ), SARG3, ARG4);
PRE_REG_READ4(long, "epoll_ctl",
int, epfd, int, op, int, fd, struct vki_epoll_event *,
event);
- if (ARG2 != VKI_EPOLL_CTL_DEL)
- PRE_MEM_READ( "epoll_ctl(event)", ARG4, sizeof(struct vki_epoll_event)
);
+ if (ARG2 != VKI_EPOLL_CTL_DEL) {
+ struct vki_epoll_event *event = (struct vki_epoll_event *) ARG4;
+ PRE_MEM_READ( "epoll_ctl(event.events)", (Addr) &event->events,
+ sizeof(__vki_u32) );
+ PRE_MEM_READ( "epoll_ctl(event.data)", (Addr) &event->data,
+ sizeof(__vki_u64) );
+ }
}
PRE(sys_epoll_wait)
But as pointed out in the Fedora bug report
(https://bugzilla.redhat.com/show_bug.cgi?id=1844778) even that might not be
completely correct since epoll_data_t is a union of both 32- and 64-bit fields
and so might only have seen half of the 64-bits be defined.
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