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tile: work around bug in the generic sys_llseek

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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: Chris Metcalf <cmetcalf@tilera.com>
Cc: stable@kernel.org [v3.6 onwards]
This commit is contained in:
Chris Metcalf 2013-03-04 11:19:09 -05:00
parent 6dbe51c251
commit 5a114b9866
2 changed files with 16 additions and 0 deletions
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3
arch/tile/include/asm/compat.h
View File

@ -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);

13
arch/tile/kernel/compat.c
View File

@ -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