From c4c0d19d39d26c5f58633f8fcca75f03b2854fc0 Mon Sep 17 00:00:00 2001 From: Zhihao Cheng Date: Tue, 16 Jun 2020 15:11:42 +0800 Subject: [PATCH] ubifs: Limit dumping length by size of memory which is allocated for the node To prevent memory out-of-bounds accessing in ubifs_dump_node(), actual dumping length should be restricted by another condition(size of memory which is allocated for the node). This patch handles following situations (These situations may be caused by bit flipping due to hardware error, writing bypass ubifs, unknown bugs in ubifs, etc.): 1. bad node_len: Dumping data according to 'ch->len' which may exceed the size of memory allocated for node. 2. bad node content: Some kinds of node can record additional data, eg. index node and orphan node, make sure the size of additional data not beyond the node length. 3. node_type changes: Read data according to type A, but expected type B, before that, node is allocated according to type B's size. Length of type A node is greater than type B node. Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger --- fs/ubifs/debug.c | 63 ++++++++++++++++++++++++++++++++++++++++++++------------ fs/ubifs/debug.h | 3 ++- 2 files changed, 52 insertions(+), 14 deletions(-) diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c index 8cc0575..7077413 100644 --- a/fs/ubifs/debug.c +++ b/fs/ubifs/debug.c @@ -291,9 +291,9 @@ void ubifs_dump_inode(struct ubifs_info *c, const struct inode *inode) kfree(pdent); } -void ubifs_dump_node(const struct ubifs_info *c, const void *node) +void ubifs_dump_node(const struct ubifs_info *c, const void *node, int node_len) { - int i, n; + int i, n, type, safe_len, max_node_len, min_node_len; union ubifs_key key; const struct ubifs_ch *ch = node; char key_buf[DBG_KEY_BUF_LEN]; @@ -306,10 +306,40 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) return; } + /* Skip dumping unknown type node */ + type = ch->node_type; + if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) { + pr_err("node type %d was not recognized\n", type); + return; + } + spin_lock(&dbg_lock); dump_ch(node); - switch (ch->node_type) { + if (c->ranges[type].max_len == 0) { + max_node_len = min_node_len = c->ranges[type].len; + } else { + max_node_len = c->ranges[type].max_len; + min_node_len = c->ranges[type].min_len; + } + safe_len = le32_to_cpu(ch->len); + safe_len = safe_len > 0 ? safe_len : 0; + safe_len = min3(safe_len, max_node_len, node_len); + if (safe_len < min_node_len) { + pr_err("node len(%d) is too short for %s, left %d bytes:\n", + safe_len, dbg_ntype(type), + safe_len > UBIFS_CH_SZ ? + safe_len - (int)UBIFS_CH_SZ : 0); + if (safe_len > UBIFS_CH_SZ) + print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 32, 1, + (void *)node + UBIFS_CH_SZ, + safe_len - UBIFS_CH_SZ, 0); + goto out_unlock; + } + if (safe_len != le32_to_cpu(ch->len)) + pr_err("\ttruncated node length %d\n", safe_len); + + switch (type) { case UBIFS_PAD_NODE: { const struct ubifs_pad_node *pad = node; @@ -453,7 +483,8 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) pr_err("\tnlen %d\n", nlen); pr_err("\tname "); - if (nlen > UBIFS_MAX_NLEN) + if (nlen > UBIFS_MAX_NLEN || + nlen > safe_len - UBIFS_DENT_NODE_SZ) pr_err("(bad name length, not printing, bad or corrupted node)"); else { for (i = 0; i < nlen && dent->name[i]; i++) @@ -467,7 +498,6 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) case UBIFS_DATA_NODE: { const struct ubifs_data_node *dn = node; - int dlen = le32_to_cpu(ch->len) - UBIFS_DATA_NODE_SZ; key_read(c, &dn->key, &key); pr_err("\tkey %s\n", @@ -475,10 +505,13 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) pr_err("\tsize %u\n", le32_to_cpu(dn->size)); pr_err("\tcompr_typ %d\n", (int)le16_to_cpu(dn->compr_type)); - pr_err("\tdata size %d\n", dlen); - pr_err("\tdata:\n"); + pr_err("\tdata size %u\n", + le32_to_cpu(ch->len) - (unsigned int)UBIFS_DATA_NODE_SZ); + pr_err("\tdata (length = %d):\n", + safe_len - (int)UBIFS_DATA_NODE_SZ); print_hex_dump(KERN_ERR, "\t", DUMP_PREFIX_OFFSET, 32, 1, - (void *)&dn->data, dlen, 0); + (void *)&dn->data, + safe_len - (int)UBIFS_DATA_NODE_SZ, 0); break; } case UBIFS_TRUN_NODE: @@ -495,9 +528,12 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) case UBIFS_IDX_NODE: { const struct ubifs_idx_node *idx = node; + int max_child_cnt = (safe_len - UBIFS_IDX_NODE_SZ) / + (ubifs_idx_node_sz(c, 1) - + UBIFS_IDX_NODE_SZ); - n = le16_to_cpu(idx->child_cnt); - pr_err("\tchild_cnt %d\n", n); + n = min_t(int, le16_to_cpu(idx->child_cnt), max_child_cnt); + pr_err("\tchild_cnt %d\n", (int)le16_to_cpu(idx->child_cnt)); pr_err("\tlevel %d\n", (int)le16_to_cpu(idx->level)); pr_err("\tBranches:\n"); @@ -525,7 +561,7 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) le64_to_cpu(orph->cmt_no) & LLONG_MAX); pr_err("\tlast node flag %llu\n", (unsigned long long)(le64_to_cpu(orph->cmt_no)) >> 63); - n = (le32_to_cpu(ch->len) - UBIFS_ORPH_NODE_SZ) >> 3; + n = (safe_len - UBIFS_ORPH_NODE_SZ) >> 3; pr_err("\t%d orphan inode numbers:\n", n); for (i = 0; i < n; i++) pr_err("\t ino %llu\n", @@ -537,9 +573,10 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node) break; } default: - pr_err("node type %d was not recognized\n", - (int)ch->node_type); + pr_err("node type %d was not recognized\n", type); } + +out_unlock: spin_unlock(&dbg_lock); } diff --git a/fs/ubifs/debug.h b/fs/ubifs/debug.h index 7763639..42610fa 100644 --- a/fs/ubifs/debug.h +++ b/fs/ubifs/debug.h @@ -242,7 +242,8 @@ const char *dbg_get_key_dump(const struct ubifs_info *c, const char *dbg_snprintf_key(const struct ubifs_info *c, const union ubifs_key *key, char *buffer, int len); void ubifs_dump_inode(struct ubifs_info *c, const struct inode *inode); -void ubifs_dump_node(const struct ubifs_info *c, const void *node); +void ubifs_dump_node(const struct ubifs_info *c, const void *node, + int node_len); void ubifs_dump_budget_req(const struct ubifs_budget_req *req); void ubifs_dump_lstats(const struct ubifs_lp_stats *lst); void ubifs_dump_budg(struct ubifs_info *c, const struct ubifs_budg_info *bi); -- 2.7.4