From: "Steven Rostedt (Google)" <rostedt@goodmis.org> mainline inclusion from mainline-v6.1-rc1 commit 0934ae9977c27133449b6dd8c6213970e7eece38 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICY479 CVE: CVE-2022-50255 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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 Link: https://lkml.kernel.org/r/20221012104534.826549315@goodmis.org Cc: stable@vger.kernel.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Tom Zanussi <zanussi@kernel.org> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Tom Zanussi <zanussi@kernel.org> Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Conflicts: kernel/trace/trace.h [The macro FAULT_STRING was introduced in commit bd82631d7ccdc and reverted in commit 2e9906f84fc. The net effect of these changes was merely the addition of the 'FAULT_STRING' macro within trace.h. So skip these two patches and directly adapt to this final outcome.] Signed-off-by: Tengda Wu <wutengda2@huawei.com> --- kernel/trace/trace.h | 2 ++ kernel/trace/trace_events_synth.c | 23 +++++++++++++++++------ 2 files changed, 19 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 06c6c97e1136..139d4e47489d 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -114,6 +114,8 @@ enum trace_type { unlikely(__ret_warn_once); \ }) +#define FAULT_STRING "(fault)" + /* * syscalls are special, and need special handling, this is why * they are not included in trace_entries.h diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index 5e677aa972b0..eace14438d31 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -17,6 +17,8 @@ /* for gfp flag names */ #include <linux/trace_events.h> #include <trace/events/mmflags.h> +#include "trace_probe.h" +#include "trace_probe_kernel.h" #include "trace_synth.h" @@ -400,6 +402,7 @@ static unsigned int trace_string(struct synth_trace_event *entry, { unsigned int len = 0; char *str_field; + int ret; if (is_dynamic) { u32 data_offset; @@ -408,19 +411,27 @@ static unsigned int trace_string(struct synth_trace_event *entry, data_offset += event->n_u64 * sizeof(u64); data_offset += data_size; - str_field = (char *)entry + data_offset; - - len = strlen(str_val) + 1; - strscpy(str_field, str_val, len); + len = kern_fetch_store_strlen((unsigned long)str_val); data_offset |= len << 16; *(u32 *)&entry->fields[*n_u64] = data_offset; + ret = kern_fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry); + (*n_u64)++; } else { str_field = (char *)&entry->fields[*n_u64]; - strscpy(str_field, str_val, STR_VAR_LEN_MAX); +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if ((unsigned long)str_val < TASK_SIZE) + ret = strncpy_from_user_nofault(str_field, str_val, STR_VAR_LEN_MAX); + else +#endif + ret = strncpy_from_kernel_nofault(str_field, str_val, STR_VAR_LEN_MAX); + + if (ret < 0) + strcpy(str_field, FAULT_STRING); + (*n_u64) += STR_VAR_LEN_MAX / sizeof(u64); } @@ -453,7 +464,7 @@ static notrace void trace_event_raw_event_synth(void *__data, val_idx = var_ref_idx[field_pos]; str_val = (char *)(long)var_ref_vals[val_idx]; - len = strlen(str_val) + 1; + len = kern_fetch_store_strlen((unsigned long)str_val); fields_size += len; } -- 2.34.1