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powerpc: Fix fallocate and fadvise64_64 compat parameter combination

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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: 57f48b4b74 ("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
This commit is contained in:
Rohan McLure 2022-09-21 16:55:48 +10:00 committed by Michael Ellerman
parent 620f5c59c8
commit 016ff72bd2
3 changed files with 15 additions and 15 deletions
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12
arch/powerpc/include/asm/syscalls.h
View file

@ -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,

14
arch/powerpc/kernel/sys_ppc32.c
View file

@ -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));
}

4
arch/powerpc/kernel/syscalls.c
View file

@ -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)