Re: kern/53800: ptrace crashes

[Kamil Rytarowski <n54%gmx.com@localhost>]

The following reply was made to PR kern/53800; it has been noted by GNATS.

From: Kamil Rytarowski <n54%gmx.com@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/53800: ptrace crashes
Date: Wed, 19 Dec 2018 18:10:04 +0100

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 From: Kamil Rytarowski <n54%gmx.com@localhost>
 To: gnats-bugs%NetBSD.org@localhost
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 Subject: Re: kern/53800: ptrace crashes
 References: <pr-kern-53800%gnats.netbsd.org@localhost>
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 On 19.12.2018 16:55, Christos Zoulas wrote:
 > The following reply was made to PR kern/53800; it has been noted by GNA=
 TS.
 >=20
 > From: christos%zoulas.com@localhost (Christos Zoulas)
 > To: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost,=20
 > 	gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, coypu%sdf.org@localhost
 > Cc:=20
 > Subject: Re: kern/53800: ptrace crashes
 > Date: Wed, 19 Dec 2018 10:50:44 -0500
 >=20
 >  On Dec 19,  5:40am, coypu%sdf.org@localhost (coypu%sdf.org@localhost) wrote:
 >  -- Subject: Re: kern/53800: ptrace crashes
 > =20
 >  | The following reply was made to PR kern/53800; it has been noted by =
 GNATS.
 >  |=20
 >  | From: coypu%sdf.org@localhost
 >  | To: gnats-bugs%NetBSD.org@localhost
 >  | Cc:=20
 >  | Subject: Re: kern/53800: ptrace crashes
 >  | Date: Wed, 19 Dec 2018 05:38:50 +0000
 >  |=20
 >  |  Looks like the problem is commented:
 >  | =20
 >  |          case PT_ATTACH:
 >  |                  /*
 >  |                   * Go ahead and set the trace flag.
 >  |                   * Save the old parent (it's reset in
 >  |                   *   _DETACH, and also in kern_exit.c:wait4()
 >  |                   * Reparent the process so that the tracing
 >  |                   *   proc gets to see all the action.
 >  | =20
 >  | =20
 >  |  But it is not reset in _DETACH.
 > =20
 >  Nope, it is reset in PT_DETACH. In fact the code works as documented..=
 =2E
 >  It crashes because the code jumps to 0. Since PT_DETACH works like
 >  PT_CONTINUE, passing NULL as the 3rd argument to ptrace will do that :=
 -)
 >  Try passing (void *)1 and it will work. Arguably this is not a very
 >  useful or expected feature, but I don't think that changing it is
 >  wise...
 > =20
 >  christos
 > =20
 >=20
 
 Linux has BSD4.3 ptrace(2) compat that is broken, not the other way
 around. Nothing to be changed here, except Linux (but it won't happen).
 
 
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