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| author | Al Viro <viro@zeniv.linux.org.uk> | 2020-07-20 02:21:51 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-07-21 18:23:55 -0700 |
| commit | 7780918b36489f0b2f9a3749d7be00c2ceaec513 (patch) | |
| tree | 2e4b1f03e9d0813a03d63aaa2cbc714934212686 | |
| parent | e0602848213587d02d146ede8ad31c269982c839 (diff) | |
| download | linux-stable-7780918b36489f0b2f9a3749d7be00c2ceaec513.tar.gz linux-stable-7780918b36489f0b2f9a3749d7be00c2ceaec513.tar.bz2 linux-stable-7780918b36489f0b2f9a3749d7be00c2ceaec513.zip | |
sparc32: fix a user-triggerable oops in clear_user()
Back in 2.1.29 the clear_user() guts (__bzero()) had been merged
with memset(). Unfortunately, while all exception handlers had been
copied, one of the exception table entries got lost. As the result,
clear_user() starting at 128*n bytes before the end of page and
spanning between 8 and 127 bytes into the next page would oops when
the second page is unmapped. It's trivial to reproduce - all
it takes is
main()
{
int fd = open("/dev/zero", O_RDONLY);
char *p = mmap(NULL, 16384, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANON, -1, 0);
munmap(p + 8192, 8192);
read(fd, p + 8192 - 128, 192);
}
which had been oopsing since March 1997. Says something about
the quality of test coverage... ;-/ And while today sparc32 port
is nearly dead, back in '97 it had been very much alive; in fact,
sparc64 had only been in mainline for 3 months by that point...
Cc: stable@kernel.org
Fixes: v2.1.29
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | arch/sparc/lib/memset.S | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/sparc/lib/memset.S b/arch/sparc/lib/memset.S index b89d42b29e34..f427f34b8b79 100644 --- a/arch/sparc/lib/memset.S +++ b/arch/sparc/lib/memset.S @@ -142,6 +142,7 @@ __bzero: ZERO_LAST_BLOCKS(%o0, 0x48, %g2) ZERO_LAST_BLOCKS(%o0, 0x08, %g2) 13: + EXT(12b, 13b, 21f) be 8f andcc %o1, 4, %g0 |