CVE-2022-50255

01/Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix reading strings from synthetic events The follow commands caused a crash: # cd /sys/kernel/tracing # echo 's:open char file[]' > dynamic_events # echo 'hist:keys=common_pid:file=filename:onchange($file).trace(open,$file)' > events/syscalls/sys_enter_openat/trigger' # echo 1 > events/synthetic/open/enable BOOM! The problem is that the synthetic event field "char file[]" will read the value given to it as a string without any memory checks to make sure the address is valid. The above example will pass in the user space address and the sythetic event code will happily call strlen() on it and then strscpy() where either one will cause an oops when accessing user space addresses. Use the helper functions from trace_kprobe and trace_eprobe that can read strings safely (and actually succeed when the address is from user space and the memory is mapped in). Now the above can show: packagekitd-1721 [000] ...2. 104.597170: open: file=/usr/lib/rpm/fileattrs/cmake.attr in:imjournal-978 [006] ...2. 104.599642: open: file=/var/lib/rsyslog/imjournal.state.tmp packagekitd-1721 [000] ...2. 104.626308: open: file=/usr/lib/rpm/fileattrs/debuginfo.attr

02/Affected products

linux: linux kernel

03/References4

• git.kernel.org/stable/c/0934ae9977c27133449b6dd8c6213970e7eece38 Patch
• git.kernel.org/stable/c/149198d0b884e4606ed1d29b330c70016d878276 Patch
• git.kernel.org/stable/c/d9c79fbcbdb6cb10c07c85040eaf615180b26c48 Patch
• git.kernel.org/stable/c/f8bae1853196b52ede50950387f5b48cf83b9815 Patch