The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: dc0a241ceaf3b7df6f1a7658b020c92682b75bfc
Gitweb: https://git.kernel.org/tip/dc0a241ceaf3b7df6f1a7658b020c92682b75bfc
Author: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
AuthorDate: Wed, 19 Feb 2025 15:53:26 -05:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 21 Feb 2025 14:21:02 +01:00
rseq: Fix rseq registration with CONFIG_DEBUG_RSEQ
With CONFIG_DEBUG_RSEQ=y, at rseq registration the read-only fields are
copied from user-space, if this copy fails the syscall returns -EFAULT
and the registration should not be activated - but it erroneously is.
Move the activation of the registration after the copy of the fields to
fix this bug.
Fixes: 7d5265ffcd8b ("rseq: Validate read-only fields under DEBUG_RSEQ config")
Signed-off-by: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250219205330.324770-1-mjeanson@xxxxxxxxxxxx
---
kernel/rseq.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/kernel/rseq.c b/kernel/rseq.c
index 442aba2..2cb1609 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -507,9 +507,6 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
return -EINVAL;
if (!access_ok(rseq, rseq_len))
return -EFAULT;
- current->rseq = rseq;
- current->rseq_len = rseq_len;
- current->rseq_sig = sig;
#ifdef CONFIG_DEBUG_RSEQ
/*
* Initialize the in-kernel rseq fields copy for validation of
@@ -522,6 +519,14 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len,
return -EFAULT;
#endif
/*
+ * Activate the registration by setting the rseq area address, length
+ * and signature in the task struct.
+ */
+ current->rseq = rseq;
+ current->rseq_len = rseq_len;
+ current->rseq_sig = sig;
+
+ /*
* If rseq was previously inactive, and has just been
* registered, ensure the cpu_id_start and cpu_id fields
* are updated before returning to user-space.
|