table->offset[i] is a u32 from firmware, but was stored into a signed int. A crafted offset like 0xFFFFFFF0 becomes -16, placing hdr 16 bytes before the table buffer. The subsequent avail check was bypassed because the negative int was promoted to a large size_t in the expression "table_sz - offset - sizeof(*hdr)", yielding a large positive avail and letting the out-of-bounds hdr->type read proceed undetected.
Store the offset as u32 and validate it with unsigned comparisons before any pointer arithmetic. Signed-off-by: Mukesh Ojha <[email protected]> --- include/linux/rsc_table.h | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/include/linux/rsc_table.h b/include/linux/rsc_table.h index b78c4760d83e..f9c5628e16cd 100644 --- a/include/linux/rsc_table.h +++ b/include/linux/rsc_table.h @@ -338,17 +338,22 @@ static inline int rsc_table_for_each_entry(struct resource_table *table, int i, ret; for (i = 0; i < table->num; i++) { - int offset = table->offset[i]; - struct fw_rsc_hdr *hdr = (void *)table + offset; - int avail = table_sz - offset - sizeof(*hdr); - int rsc_offset = offset + sizeof(*hdr); - void *rsc = (void *)hdr + sizeof(*hdr); + u32 offset = table->offset[i]; + struct fw_rsc_hdr *hdr; + int avail, rsc_offset; + void *rsc; - if (avail < 0) { + if (offset < sizeof(*table) || offset >= table_sz || + table_sz - offset < sizeof(*hdr)) { dev_err(dev, "rsc table is truncated\n"); return -EINVAL; } + hdr = (void *)table + offset; + avail = table_sz - offset - sizeof(*hdr); + rsc_offset = offset + sizeof(*hdr); + rsc = (void *)hdr + sizeof(*hdr); + ret = cb(hdr->type, rsc, rsc_offset, avail, data); if (ret) return ret; -- 2.53.0
