powerpc: Fix fallocate and fadvise64_64 compat parameter combination

As reported[1] by Arnd, the arch-specific fadvise64_64 and fallocate
compatibility handlers assume parameters are passed with 32-bit
big-endian ABI. This affects the assignment of odd-even parameter pairs
to the high or low words of a 64-bit syscall parameter.

Fix fadvise64_64 fallocate compat handlers to correctly swap upper/lower
32 bits conditioned on endianness.

A future patch will replace the arch-specific compat fallocate with an
asm-generic implementation. This patch is intended for ease of
back-port.

[1]: https://lore.kernel.org/all/be29926f-226e-48dc-871a-e29a54e80583@www.fastmail.com/

Fixes: 57f48b4b74e7 ("powerpc/compat_sys: swap hi/lo parts of 64-bit syscall args in LE mode")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-9-rmclure@linux.ibm.com

diff --git a/arch/powerpc/include/asm/syscalls.h b/arch/powerpc/include/asm/syscalls.h
index 21c2faaa29574124aaf12dba126c879ed033e766..ae7ca59f6267617f6f639f88b05ffd24a7952cc9 100644 (file)
--- a/arch/powerpc/include/asm/syscalls.h
+++ b/arch/powerpc/include/asm/syscalls.h
@@ -8,6 +8,18 @@
 #include <linux/types.h>
 #include <linux/compat.h>
 
+/*
+ * long long munging:
+ * The 32 bit ABI passes long longs in an odd even register pair.
+ * High and low parts are swapped depending on endian mode,
+ * so define a macro (similar to mips linux32) to handle that.
+ */
+#ifdef __LITTLE_ENDIAN__
+#define merge_64(low, high) (((u64)high << 32) | low)
+#else
+#define merge_64(high, low) (((u64)high << 32) | low)
+#endif
+
 struct rtas_args;
 
 long sys_mmap(unsigned long addr, size_t len,

diff --git a/arch/powerpc/kernel/sys_ppc32.c b/arch/powerpc/kernel/sys_ppc32.c
index f4edcc9489fb05997d3342c51fd49ec720686121..ba363328da2bc9888acbb4d3ba2f5a108a160a62 100644 (file)
--- a/arch/powerpc/kernel/sys_ppc32.c
+++ b/arch/powerpc/kernel/sys_ppc32.c
@@ -56,18 +56,6 @@ unsigned long compat_sys_mmap2(unsigned long addr, size_t len,
        return sys_mmap(addr, len, prot, flags, fd, pgoff << 12);
 }
 
-/* 
- * long long munging:
- * The 32 bit ABI passes long longs in an odd even register pair.
- * High and low parts are swapped depending on endian mode,
- * so define a macro (similar to mips linux32) to handle that.
- */
-#ifdef __LITTLE_ENDIAN__
-#define merge_64(low, high) ((u64)high << 32) | low
-#else
-#define merge_64(high, low) ((u64)high << 32) | low
-#endif
-
 compat_ssize_t compat_sys_pread64(unsigned int fd, char __user *ubuf, compat_size_t count,
                             u32 reg6, u32 pos1, u32 pos2)
 {
@@ -94,7 +82,7 @@ int compat_sys_truncate64(const char __user * path, u32 reg4,
 long compat_sys_fallocate(int fd, int mode, u32 offset1, u32 offset2,
                                     u32 len1, u32 len2)
 {
-       return ksys_fallocate(fd, mode, ((loff_t)offset1 << 32) | offset2,
+       return ksys_fallocate(fd, mode, merge_64(offset1, offset2),
                             merge_64(len1, len2));
 }
 

diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
index fc999140bc27e94229856e80f0cac221f87c59b8..abc3fbb3c4902a7c9556183e9b71c8d529aba65d 100644 (file)
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -98,8 +98,8 @@ long ppc64_personality(unsigned long personality)
 long ppc_fadvise64_64(int fd, int advice, u32 offset_high, u32 offset_low,
                      u32 len_high, u32 len_low)
 {
-       return ksys_fadvise64_64(fd, (u64)offset_high << 32 | offset_low,
-                                (u64)len_high << 32 | len_low, advice);
+       return ksys_fadvise64_64(fd, merge_64(offset_high, offset_low),
+                                merge_64(len_high, len_low), advice);
 }
 
 SYSCALL_DEFINE0(switch_endian)