nfp: validate rtsym accesses fall within the symbol

With the accesses to rtsyms now all going via special helpers
we can easily make sure the driver is not reading past the
end of the symbol.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Francois H. Theron <francois.theron@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_rtsym.c

@@ -39,6 +39,8 @@
  *          Espen Skoglund <espen.skoglund@netronome.com>
  *          Francois H. Theron <francois.theron@netronome.com>
  */
+
+#include <asm/unaligned.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -285,15 +287,23 @@ nfp_rtsym_to_dest(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 int __nfp_rtsym_read(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 		     u8 action, u8 token, u64 off, void *buf, size_t len)
 {
+	u64 sym_size = nfp_rtsym_size(sym);
 	u32 cpp_id;
 	u64 addr;
 	int err;
 
+	if (off > sym_size) {
+		nfp_err(cpp, "rtsym '%s': read out of bounds: off: %lld + len: %zd > size: %lld\n",
+			sym->name, off, len, sym_size);
+		return -ENXIO;
+	}
+	len = min_t(size_t, len, sym_size - off);
+
 	if (sym->type == NFP_RTSYM_TYPE_ABS) {
-		__le64 tmp = cpu_to_le64(sym->addr);
+		u8 tmp[8];
 
-		len = min(len, sizeof(tmp));
-		memcpy(buf, &tmp, len);
+		put_unaligned_le64(sym->addr, tmp);
+		memcpy(buf, &tmp[off], len);
 
 		return len;
 	}
@@ -318,6 +328,12 @@ int __nfp_rtsym_readl(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 	u64 addr;
 	int err;
 
+	if (off + 4 > nfp_rtsym_size(sym)) {
+		nfp_err(cpp, "rtsym '%s': readl out of bounds: off: %lld + 4 > size: %lld\n",
+			sym->name, off, nfp_rtsym_size(sym));
+		return -ENXIO;
+	}
+
 	err = nfp_rtsym_to_dest(cpp, sym, action, token, off, &cpp_id, &addr);
 	if (err)
 		return err;
@@ -338,6 +354,12 @@ int __nfp_rtsym_readq(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 	u64 addr;
 	int err;
 
+	if (off + 8 > nfp_rtsym_size(sym)) {
+		nfp_err(cpp, "rtsym '%s': readq out of bounds: off: %lld + 8 > size: %lld\n",
+			sym->name, off, nfp_rtsym_size(sym));
+		return -ENXIO;
+	}
+
 	if (sym->type == NFP_RTSYM_TYPE_ABS) {
 		*value = sym->addr;
 		return 0;
@@ -359,10 +381,18 @@ int nfp_rtsym_readq(struct nfp_cpp *cpp, const struct nfp_rtsym *sym, u64 off,
 int __nfp_rtsym_write(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 		      u8 action, u8 token, u64 off, void *buf, size_t len)
 {
+	u64 sym_size = nfp_rtsym_size(sym);
 	u32 cpp_id;
 	u64 addr;
 	int err;
 
+	if (off > sym_size) {
+		nfp_err(cpp, "rtsym '%s': write out of bounds: off: %lld + len: %zd > size: %lld\n",
+			sym->name, off, len, sym_size);
+		return -ENXIO;
+	}
+	len = min_t(size_t, len, sym_size - off);
+
 	err = nfp_rtsym_to_dest(cpp, sym, action, token, off, &cpp_id, &addr);
 	if (err)
 		return err;
@@ -383,6 +413,12 @@ int __nfp_rtsym_writel(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 	u64 addr;
 	int err;
 
+	if (off + 4 > nfp_rtsym_size(sym)) {
+		nfp_err(cpp, "rtsym '%s': writel out of bounds: off: %lld + 4 > size: %lld\n",
+			sym->name, off, nfp_rtsym_size(sym));
+		return -ENXIO;
+	}
+
 	err = nfp_rtsym_to_dest(cpp, sym, action, token, off, &cpp_id, &addr);
 	if (err)
 		return err;
@@ -403,6 +439,12 @@ int __nfp_rtsym_writeq(struct nfp_cpp *cpp, const struct nfp_rtsym *sym,
 	u64 addr;
 	int err;
 
+	if (off + 8 > nfp_rtsym_size(sym)) {
+		nfp_err(cpp, "rtsym '%s': writeq out of bounds: off: %lld + 8 > size: %lld\n",
+			sym->name, off, nfp_rtsym_size(sym));
+		return -ENXIO;
+	}
+
 	err = nfp_rtsym_to_dest(cpp, sym, action, token, off, &cpp_id, &addr);
 	if (err)
 		return err;