Fix rlimit check in precheck_file_write()

Remove a broken assumption that rlimits are 32 bits which can cause nasty things to happen on 64-bit machines if we try to write past the 2^32-1th character of a file and a larger file size limit exists.

Signed-off-by Jason Uhlenkott <[email protected]>

Quoted 6 lines · Jason Uhlenkott

Remove a broken assumption that rlimits are 32 bits which can cause nasty things to happen on 64-bit machines if we try to write past the 2^32-1th character of a file and a larger file size limit exists.

Signed-off-by Jason Uhlenkott <[email protected]>

mm/filemap.c line 3094

Quoted 12 lines

mm/filemap.c +2 -2

@@ -3088,9 +3088,9 @@
 			send_sig(SIGXFSZ, current, 0);
 			goto out;
 		}
-		if (pos > 0xFFFFFFFFULL || *count > limit - (u32)pos) {
+		if (*count > limit - pos) {
 			/* send_sig(SIGXFSZ, current, 0); */
-			*count = limit - (u32)pos;
+			*count = limit - pos;
 		}

Are you sure this is safe for all conceivable 32bit cases as well as your 64bit one ? I don't think it is looking at the overflow cases in the if that you removed checking of.