[2.6.20.17 review 58/58] Reset current->pdeath_signal on SUID binary execution (CVE-2007-3848)

Willy Tarreau
2007-08-22T09:08:40Z

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This fixes a vulnerability in the "parent process death signal"
implementation discoverd by Wojciech Purczynski of COSEINC PTE Ltd.
and iSEC Security Research.

http://marc.info/?l=bugtraq&m=118711306802632&w=2

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
fs/exec.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 0f8573a..bd1ab3f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -881,9 +881,12 @@ int flush_old_exec(struct linux_binprm * bprm)
*/
current->mm->task_size = TASK_SIZE;

- if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
- file_permission(bprm->file, MAY_READ) ||
- (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
+ if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
+ suid_keys(current);
+ current->mm->dumpable = suid_dumpable;
+ current->pdeath_signal = 0;
+ } else if (file_permission(bprm->file, MAY_READ) ||
+ (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
suid_keys(current);
current->mm->dumpable = suid_dumpable;
}
@@ -974,8 +977,10 @@ void compute_creds(struct linux_binprm *bprm)
{
int unsafe;

- if (bprm->e_uid != current->uid)
+ if (bprm->e_uid != current->uid) {
suid_keys(current);
+ current->pdeath_signal = 0;
+ }
exec_keys(current);

task_lock(current);
--
1.5.2.5

--