Don't reset uio_offset to 0 before returning. Instead, refuse to service

requests where uio_offset is not 0 to begin with.  This fixes a long-
standing bug where e.g. 'cat /proc/$$/regs' would loop forever.

MFC after:	3 weeks

2 files changed, 7 insertions, 3 deletions

diff --git a/sys/fs/procfs/procfs_dbregs.c b/sys/fs/procfs/procfs_dbregs.c
index c30f231..d985245 100644
--- a/sys/fs/procfs/procfs_dbregs.c
+++ b/sys/fs/procfs/procfs_dbregs.c
@@ -95,6 +95,9 @@ procfs_doprocdbregs(PFS_FILL_ARGS)
 	int wrap32 = 0;
 #endif
 
+	if (uio->uio_offset != 0)
+		return (0);
+
 	PROC_LOCK(p);
 	KASSERT(p->p_lock > 0, ("proc not held"));
 	if (p_candebug(td, p) != 0) {
@@ -128,6 +131,5 @@ procfs_doprocdbregs(PFS_FILL_ARGS)
 	}
 	PROC_UNLOCK(p);
 
-	uio->uio_offset = 0;
 	return (error);
 }
diff --git a/sys/fs/procfs/procfs_regs.c b/sys/fs/procfs/procfs_regs.c
index cba2b7b..481c053 100644
--- a/sys/fs/procfs/procfs_regs.c
+++ b/sys/fs/procfs/procfs_regs.c
@@ -89,8 +89,11 @@ procfs_doprocregs(PFS_FILL_ARGS)
 	int wrap32 = 0;
 #endif
 
+	if (uio->uio_offset != 0)
+		return (0);
+
 	PROC_LOCK(p);
-	KASSERT(p->p_lock > 0, ("proc not held"));
+	PROC_ASSERT_HELD(p);
 	if (p_candebug(td, p)) {
 		PROC_UNLOCK(p);
 		return (EPERM);
@@ -122,6 +125,5 @@ procfs_doprocregs(PFS_FILL_ARGS)
 	}
 	PROC_UNLOCK(p);
 
-	uio->uio_offset = 0;
 	return (error);
 }