The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applicationsThere is no fixed version for Centos:6 perf.
Note: Versions mentioned in the description apply only to the upstream perf package and not the perf package as distributed by Centos.
See How to fix? for Centos:6 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
perf: Fix refcount warning on event->mmap_count increment
When calling refcount_inc(&event->mmap_count) inside perf_mmap_rb(), the following warning is triggered:
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25
PoC:
struct perf_event_attr attr = {0};
int fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
int victim = syscall(__NR_perf_event_open, &attr, 0, -1, fd,
PERF_FLAG_FD_OUTPUT);
mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);
This occurs when creating a group member event with the flag PERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing the event triggers the warning.
Since the event has copied the output_event in perf_event_set_output(), event->rb is set. As a result, perf_mmap_rb() calls refcount_inc(&event->mmap_count) when event->mmap_count = 0.
Disallow the case when event->mmap_count = 0. This also prevents two events from updating the same user_page.