6.8-stable review patch. If anyone has any objections, please let me know.
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From: Paul Moore paul@paul-moore.com
[ Upstream commit eaf0e7a3d2711018789e9fdb89191d19aa139c47 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- security/security.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/security/security.c b/security/security.c index fb7505c734853..a344b8fa5530d 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;