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cred: switch to using atomic_long_t

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commit f8fa5d76925991976b3e7076f9d1052515ec1fca upstream.

There are multiple ways to grab references to credentials, and the only
protection we have against overflowing it is the memory required to do
so.

With memory sizes only moving in one direction, let's bump the reference
count to 64-bit and move it outside the realm of feasibly overflowing.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Axboe
2023-12-15 13:24:10 -07:00
committed by Greg Kroah-Hartman
parent 03b50868ae
commit 2623cf1fe8
2 changed files with 36 additions and 36 deletions
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8
include/linux/cred.h
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@@ -109,7 +109,7 @@ static inline int groups_search(const struct group_info *group_info, kgid_t grp)
* same context as task->real_cred.
*/
struct cred {
atomic_t usage;
atomic_long_t usage;
#ifdef CONFIG_DEBUG_CREDENTIALS
atomic_t subscribers; /* number of processes subscribed */
void *put_addr;
@@ -227,7 +227,7 @@ static inline bool cap_ambient_invariant_ok(const struct cred *cred)
*/
static inline struct cred *get_new_cred(struct cred *cred)
{
atomic_inc(&cred->usage);
atomic_long_inc(&cred->usage);
return cred;
}
@@ -259,7 +259,7 @@ static inline const struct cred *get_cred_rcu(const struct cred *cred)
struct cred *nonconst_cred = (struct cred *) cred;
if (!cred)
return NULL;
if (!atomic_inc_not_zero(&nonconst_cred->usage))
if (!atomic_long_inc_not_zero(&nonconst_cred->usage))
return NULL;
validate_creds(cred);
nonconst_cred->non_rcu = 0;
@@ -283,7 +283,7 @@ static inline void put_cred(const struct cred *_cred)
if (cred) {
validate_creds(cred);
if (atomic_dec_and_test(&(cred)->usage))
if (atomic_long_dec_and_test(&(cred)->usage))
__put_cred(cred);
}
}