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Commit 5a114b98 authored by Chris Metcalf's avatar Chris Metcalf
Browse files

tile: work around bug in the generic sys_llseek 



sys_llseek should specify the high and low 32-bit seek values as "unsigned
int" but instead it specifies "unsigned long".  Since compat syscall
arguments are always sign-extended on tile, this means that a seek value
of 0xffffffff will be incorrectly interpreted as a value of -1ULL.

To avoid the risk of breaking binary compatibility on architectures
that already use sys_llseek this way, we follow the same path as MIPS
and provide a wrapper override.

Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
Cc: stable@kernel.org [v3.6 onwards]
parent 6dbe51c2

arch/tile/include/asm/compat.h

+3 −0
Original line number Diff line number Diff line
@@ -288,6 +288,9 @@ long compat_sys_sync_file_range2(int fd, unsigned int flags, 
long compat_sys_fallocate(int fd, int mode,

			  u32 offset_lo, u32 offset_hi,

			  u32 len_lo, u32 len_hi);

long compat_sys_llseek(unsigned int fd, unsigned int offset_high,

		       unsigned int offset_low, loff_t __user * result,

		       unsigned int origin);



/* Assembly trampoline to avoid clobbering r0. */

long _compat_sys_rt_sigreturn(void);

arch/tile/kernel/compat.c

+13 −0
Original line number Diff line number Diff line
@@ -76,6 +76,18 @@ long compat_sys_fallocate(int fd, int mode, 
			     ((loff_t)len_hi << 32) | len_lo);

}



/*

 * Avoid bug in generic sys_llseek() that specifies offset_high and

 * offset_low as "unsigned long", thus making it possible to pass

 * a sign-extended high 32 bits in offset_low.

 */

long compat_sys_llseek(unsigned int fd, unsigned int offset_high,

		       unsigned int offset_low, loff_t __user * result,

		       unsigned int origin)

{

	return sys_llseek(fd, offset_high, offset_low, result, origin);

}

 

/* Provide the compat syscall number to call mapping. */

#undef __SYSCALL

#define __SYSCALL(nr, call) [nr] = (call),
@@ -83,6 +95,7 @@ long compat_sys_fallocate(int fd, int mode, 
/* See comments in sys.c */

#define compat_sys_fadvise64_64 sys32_fadvise64_64

#define compat_sys_readahead sys32_readahead

#define sys_llseek compat_sys_llseek



/* Call the assembly trampolines where necessary. */

#define compat_sys_rt_sigreturn _compat_sys_rt_sigreturn