3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Jeremy Cline jcline@redhat.com
commit 7b6924d94a60c6b8c1279ca003e8744e6cd9e8b1 upstream.
'type' is user-controlled, so sanitize it after the bounds check to avoid using it in speculative execution. This covers the following potential gadgets detected with the help of smatch:
* fs/ext4/super.c:5741 ext4_quota_read() warn: potential spectre issue 'sb_dqopt(sb)->files' [r] * fs/ext4/super.c:5778 ext4_quota_write() warn: potential spectre issue 'sb_dqopt(sb)->files' [r] * fs/f2fs/super.c:1552 f2fs_quota_read() warn: potential spectre issue 'sb_dqopt(sb)->files' [r] * fs/f2fs/super.c:1608 f2fs_quota_write() warn: potential spectre issue 'sb_dqopt(sb)->files' [r] * fs/quota/dquot.c:412 mark_info_dirty() warn: potential spectre issue 'sb_dqopt(sb)->info' [w] * fs/quota/dquot.c:933 dqinit_needed() warn: potential spectre issue 'dquots' [r] * fs/quota/dquot.c:2112 dquot_commit_info() warn: potential spectre issue 'dqopt->ops' [r] * fs/quota/dquot.c:2362 vfs_load_quota_inode() warn: potential spectre issue 'dqopt->files' [w] (local cap) * fs/quota/dquot.c:2369 vfs_load_quota_inode() warn: potential spectre issue 'dqopt->ops' [w] (local cap) * fs/quota/dquot.c:2370 vfs_load_quota_inode() warn: potential spectre issue 'dqopt->info' [w] (local cap) * fs/quota/quota.c:110 quota_getfmt() warn: potential spectre issue 'sb_dqopt(sb)->info' [r] * fs/quota/quota_v2.c:84 v2_check_quota_file() warn: potential spectre issue 'quota_magics' [w] * fs/quota/quota_v2.c:85 v2_check_quota_file() warn: potential spectre issue 'quota_versions' [w] * fs/quota/quota_v2.c:96 v2_read_file_info() warn: potential spectre issue 'dqopt->info' [r] * fs/quota/quota_v2.c:172 v2_write_file_info() warn: potential spectre issue 'dqopt->info' [r]
Additionally, a quick inspection indicates there are array accesses with 'type' in quota_on() and quota_off() functions which are also addressed by this.
Cc: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Jeremy Cline jcline@redhat.com Signed-off-by: Jan Kara jack@suse.cz [bwh: Backported to 3.16: The maximum valid quota type is command-dependent. Introduce a local variable rather than repeating the expression.] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -17,6 +17,7 @@ #include <linux/quotaops.h> #include <linux/types.h> #include <linux/writeback.h> +#include <linux/nospec.h>
static int check_quotactl_permission(struct super_block *sb, int type, int cmd, qid_t id) @@ -405,10 +406,12 @@ static int quota_rmxquota(struct super_b static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr, struct path *path) { + unsigned int max_quotas = XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS; int ret;
- if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS)) + if (type >= max_quotas) return -EINVAL; + type = array_index_nospec(type, max_quotas); if (!sb->s_qcop) return -ENOSYS;