commit: 5a114b98661e3aaa0ac085eb931584dce3b0ef9b
From: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Date: Mon, 4 Mar 2013 11:19:09 -0500
Subject: 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: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: stable@xxxxxxxxxx [v3.6 onwards]
---
arch/tile/include/asm/compat.h | 3 +++
arch/tile/kernel/compat.c | 13 +++++++++++++
2 files changed, 16 insertions(+)
diff --git a/arch/tile/include/asm/compat.h b/arch/tile/include/asm/compat.h
index 001d418..78f1f2d 100644
--- a/arch/tile/include/asm/compat.h
+++ b/arch/tile/include/asm/compat.h
@@ -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);
diff --git a/arch/tile/kernel/compat.c b/arch/tile/kernel/compat.c
index 7f72401..69034e2 100644
--- a/arch/tile/kernel/compat.c
+++ b/arch/tile/kernel/compat.c
@@ -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
--
1.7.10.4
--
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