'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 Cc: stable@vger.kernel.org Signed-off-by: Jeremy Cline jcline@redhat.com ---
This patch isn't going to cleanly apply to stable without the "fs/quota: Replace XQM_MAXQUOTAS usage with MAXQUOTAS" patch, but I'm not sure that patch is really stable material and XQM_MAXQUOTAS has been 3 since pre-v4.4 so the end result will be the same even if that patch isn't backported.
fs/quota/quota.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/quota/quota.c b/fs/quota/quota.c index d403392d8a0f..f0cbf58ad4da 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -18,6 +18,7 @@ #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) @@ -701,6 +702,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
if (type >= MAXQUOTAS) return -EINVAL; + type = array_index_nospec(type, MAXQUOTAS); /* * Quota not supported on this fs? Check this before s_quota_types * since they needn't be set if quota is not supported at all.