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authorKees Cook <keescook@chromium.org>2016-05-17 12:14:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-17 13:56:53 -0700
commitcb6fd68fdd4a94880a99ad8515844c7a25e50d3e (patch)
tree766b14f48de74fcc5bac718599070fd3aab7fcee
parent7f427d3a6029331304f91ef4d7cf646f054216d2 (diff)
exec: clarify reasoning for euid/egid reset
This section of code initially looks redundant, but is required. This improves the comment to explain more clearly why the reset is needed. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/exec.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/exec.c b/fs/exec.c
index c4010b8207a1..a98b21d47385 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1387,7 +1387,12 @@ static void bprm_fill_uid(struct linux_binprm *bprm)
kuid_t uid;
kgid_t gid;
- /* clear any previous set[ug]id data from a previous binary */
+ /*
+ * Since this can be called multiple times (via prepare_binprm),
+ * we must clear any previous work done when setting set[ug]id
+ * bits from any earlier bprm->file uses (for example when run
+ * first for a setuid script then again for its interpreter).
+ */
bprm->cred->euid = current_euid();
bprm->cred->egid = current_egid();