diff options
| author | André Rösti <an.roesti@gmail.com> | 2024-03-12 00:17:04 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-04-03 16:19:44 +0300 |
| commit | 3e5222a17914f663e56c5ffca15586cf0960b4b3 (patch) | |
| tree | 79686f89e77557a3e73d790cbc7f826f5c4cb6c8 | |
| parent | 936381380ae83563d328ab729251d8bc40581fac (diff) | |
| download | linux-3e5222a17914f663e56c5ffca15586cf0960b4b3.tar.xz | |
entry: Respect changes to system call number by trace_sys_enter()
[ Upstream commit fb13b11d53875e28e7fbf0c26b288e4ea676aa9f ]
When a probe is registered at the trace_sys_enter() tracepoint, and that
probe changes the system call number, the old system call still gets
executed. This worked correctly until commit b6ec41346103 ("core/entry:
Report syscall correctly for trace and audit"), which removed the
re-evaluation of the syscall number after the trace point.
Restore the original semantics by re-evaluating the system call number
after trace_sys_enter().
The performance impact of this re-evaluation is minimal because it only
takes place when a trace point is active, and compared to the actual trace
point overhead the read from a cache hot variable is negligible.
Fixes: b6ec41346103 ("core/entry: Report syscall correctly for trace and audit")
Signed-off-by: André Rösti <an.roesti@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240311211704.7262-1-an.roesti@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | kernel/entry/common.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/entry/common.c b/kernel/entry/common.c index be61332c66b5..ccf2b1e1b40b 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -77,8 +77,14 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, /* Either of the above might have changed the syscall number */ syscall = syscall_get_nr(current, regs); - if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT)) + if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT)) { trace_sys_enter(regs, syscall); + /* + * Probes or BPF hooks in the tracepoint may have changed the + * system call number as well. + */ + syscall = syscall_get_nr(current, regs); + } syscall_enter_audit(regs, syscall); |