Commit 016ff72b authored by Rohan McLure's avatar Rohan McLure Committed by Michael Ellerman
Browse files

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: 57f48b4b ("powerpc/compat_sys: swap hi/lo parts of 64-bit syscall args in LE mode")
Reported-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarRohan McLure <rmclure@linux.ibm.com>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-9-rmclure@linux.ibm.com
parent 620f5c59

arch/powerpc/include/asm/syscalls.h

+12 −0
Original line number Diff line number Diff line
@@ -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,

arch/powerpc/kernel/sys_ppc32.c

+1 −13
Original line number Diff line number Diff line
@@ -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));

}

arch/powerpc/kernel/syscalls.c

+2 −2
Original line number Diff line number Diff line
@@ -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)