Stanislav Kinsburskiy <skinsbur...@virtuozzo.com> writes:
> Posix acl is used to convert of an extended attribute, provided by user to
> ext4 attributes. In particular to I-mode in case of ACL_TYPE_ACCESS request.
> IOW, this object is allocated, used for convertion, not stored anywhere and
> must be freed.
> However posix_acl_update_mode() can zerofy the pointer to support
> ext4_set_acl() logic, but then the object is leaked.
> So, fix it by releasing new temporary pointer with the same value instead of
> acl pointer.
So you are telling me that:
ext4_xattr_set_acl
L1 acl = posix_acl_from_xattr
L2 -> ext4_set_acl(handle, inode, type, acl)
L3 ->posix_acl_update_mode(inode, &inode->i_mode, &acl)
*acl = NULL;
You are saying that instruction above can affect value at L1?
HOW? acl passed to ext4_set_acl() by value, so
posix_acl_update_mode() can affect value only in L2 and L3 but not L1. Stas, have you drunk a lousy beer today? > > https://jira.sw.ru/browse/PSBM-81384 > > Signed-off-by: Stanislav Kinsburskiy <skinsbur...@virtuozzo.com> > --- > fs/ext4/acl.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c > index 917e819..2640d7b 100644 > --- a/fs/ext4/acl.c > +++ b/fs/ext4/acl.c > @@ -403,7 +403,7 @@ ext4_xattr_set_acl(struct dentry *dentry, const char > *name, const void *value, > { > struct inode *inode = dentry->d_inode; > handle_t *handle; > - struct posix_acl *acl; > + struct posix_acl *acl, *tmp; > int error, retries = 0; > int update_mode = 0; > umode_t mode = inode->i_mode; > @@ -416,7 +416,7 @@ ext4_xattr_set_acl(struct dentry *dentry, const char > *name, const void *value, > return -EPERM; > > if (value) { > - acl = posix_acl_from_xattr(&init_user_ns, value, size); > + acl = tmp = posix_acl_from_xattr(&init_user_ns, value, size); > if (IS_ERR(acl)) > return PTR_ERR(acl); > else if (acl) { > @@ -425,7 +425,7 @@ ext4_xattr_set_acl(struct dentry *dentry, const char > *name, const void *value, > goto release_and_out; > } > } else > - acl = NULL; > + acl = tmp = NULL; > > retry: > handle = ext4_journal_start(inode, EXT4_HT_XATTR, > @@ -452,7 +452,7 @@ ext4_xattr_set_acl(struct dentry *dentry, const char > *name, const void *value, > goto retry; > > release_and_out: > - posix_acl_release(acl); > + posix_acl_release(tmp); > return error; > } >
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