| From | Greg Kroah-Hartman <> | Subject | [ 064/100] tile: work around bug in the generic sys_llseek | Date | Tue, 12 Mar 2013 15:31:49 -0700 |
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3.8-stable review patch. If anyone has any objections, please let me know.
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From: Chris Metcalf <cmetcalf@tilera.com>
commit 5a114b98661e3aaa0ac085eb931584dce3b0ef9b upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/tile/include/asm/compat.h | 3 +++ arch/tile/kernel/compat.c | 13 +++++++++++++ 2 files changed, 16 insertions(+)
--- a/arch/tile/include/asm/compat.h +++ b/arch/tile/include/asm/compat.h @@ -296,6 +296,9 @@ long compat_sys_sync_file_range2(int fd, 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); --- a/arch/tile/kernel/compat.c +++ b/arch/tile/kernel/compat.c @@ -76,6 +76,18 @@ long compat_sys_fallocate(int fd, int mo ((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 mo /* 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
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