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| author | Paul Moore <paul@paul-moore.com> | 2024-03-14 04:37:48 +0300 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2024-03-14 18:31:26 +0300 |
| commit | eaf0e7a3d2711018789e9fdb89191d19aa139c47 (patch) | |
| tree | b169f84cd0df5431f622a3a729e135606a9fae84 /security/security.c | |
| parent | a5a858f622a0aff5cdb5e271442cd01b2a01467f (diff) | |
| download | linux-eaf0e7a3d2711018789e9fdb89191d19aa139c47.tar.xz | |
lsm: handle the NULL buffer case in lsm_fill_user_ctx()
Passing a NULL buffer into the lsm_get_self_attr() syscall is a valid
way to quickly determine the minimum size of the buffer needed to for
the syscall to return all of the LSM attributes to the caller.
Unfortunately we/I broke that behavior in commit d7cf3412a9f6
("lsm: consolidate buffer size handling into lsm_fill_user_ctx()")
such that it returned an error to the caller; this patch restores the
original desired behavior of using the NULL buffer as a quick way to
correctly size the attribute buffer.
Cc: stable@vger.kernel.org
Fixes: d7cf3412a9f6 ("lsm: consolidate buffer size handling into lsm_fill_user_ctx()")
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security/security.c')
| -rw-r--r-- | security/security.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/security/security.c b/security/security.c index 5b2e0a15377d..7e118858b545 100644 --- a/security/security.c +++ b/security/security.c @@ -780,7 +780,9 @@ static int lsm_superblock_alloc(struct super_block *sb) * @id: LSM id * @flags: LSM defined flags * - * Fill all of the fields in a userspace lsm_ctx structure. + * Fill all of the fields in a userspace lsm_ctx structure. If @uctx is NULL + * simply calculate the required size to output via @utc_len and return + * success. * * Returns 0 on success, -E2BIG if userspace buffer is not large enough, * -EFAULT on a copyout error, -ENOMEM if memory can't be allocated. @@ -799,6 +801,10 @@ int lsm_fill_user_ctx(struct lsm_ctx __user *uctx, u32 *uctx_len, goto out; } + /* no buffer - return success/0 and set @uctx_len to the req size */ + if (!uctx) + goto out; + nctx = kzalloc(nctx_len, GFP_KERNEL); if (nctx == NULL) { rc = -ENOMEM; |