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tracing/user_events: Prevent same address and bit per process

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User processes register an address and bit pair for events. If the same
address and bit pair are registered multiple times in the same process,
it can cause undefined behavior when events are enabled/disabled.
When more than one are used, the bit could be turned off by another
event being disabled, while the original event is still enabled.

Prevent undefined behavior by checking the current mm to see if any
event has already been registered for the address and bit pair. Return
EADDRINUSE back to the user process if it's already being used.

Update ftrace self-test to ensure this occurs properly.

Link: https://lkml.kernel.org/r/20230425225107.8525-4-beaub@linux.microsoft.com

Suggested-by: Doug Cook <dcook@linux.microsoft.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Beau Belgrave
2023-04-25 15:51:06 -07:00
committed by Steven Rostedt (Google)
parent 17b439db21
commit 97bbce89bf
2 changed files with 49 additions and 1 deletions
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9
tools/testing/selftests/user_events/ftrace_test.c
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@@ -219,7 +219,12 @@ TEST_F(user, register_events) {
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
/* Multiple registers should result in same index */
/* Multiple registers to the same addr + bit should fail */
ASSERT_EQ(-1, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(EADDRINUSE, errno);
/* Multiple registers to same name should result in same index */
reg.enable_bit = 30;
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
@@ -242,6 +247,8 @@ TEST_F(user, register_events) {
/* Unregister */
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSUNREG, &unreg));
unreg.disable_bit = 30;
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSUNREG, &unreg));
/* Delete should work only after close and unregister */
close(self->data_fd);