linux-stable.git/kernel/acct.c, branch v4.9.337

acct: fix potential integer overflow in encode_comp_t()

2023-01-07T11:07:31+00:00

[ Upstream commit c5f31c655bcc01b6da53b836ac951c1556245305 ]

The integer overflow is descripted with following codes:
  > 317 static comp_t encode_comp_t(u64 value)
  > 318 {
  > 319         int exp, rnd;
    ......
  > 341         exp <<= MANTSIZE;
  > 342         exp += value;
  > 343         return exp;
  > 344 }

Currently comp_t is defined as type of '__u16', but the variable 'exp' is
type of 'int', so overflow would happen when variable 'exp' in line 343 is
greater than 65535.

Link: https://lkml.kernel.org/r/20210515140631.369106-3-zhengyejian1@huawei.com
Signed-off-by: Zheng Yejian 
Cc: Hanjun Guo 
Cc: Randy Dunlap 
Cc: Vlastimil Babka 
Cc: Zhang Jinhao 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

kernel/acct.c: fix the acct->needcheck check in check_free_space()

2018-01-10T08:29:51+00:00

commit 4d9570158b6260f449e317a5f9ed030c2504a615 upstream.

As Tsukada explains, the time_is_before_jiffies(acct->needcheck) check
is very wrong, we need time_is_after_jiffies() to make sys_acct() work.

Ignoring the overflows, the code should "goto out" if needcheck >
jiffies, while currently it checks "needcheck < jiffies" and thus in the
likely case check_free_space() does nothing until jiffies overflow.

In particular this means that sys_acct() is simply broken, acct_on()
sets acct->needcheck = jiffies and expects that check_free_space()
should set acct->active = 1 after the free-space check, but this won't
happen if jiffies increments in between.

This was broken by commit 32dc73086015 ("get rid of timer in
kern/acct.c") in 2011, then another (correct) commit 795a2f22a8ea
("acct() should honour the limits from the very beginning") made the
problem more visible.

Link: http://lkml.kernel.org/r/20171213133940.GA6554@redhat.com
Fixes: 32dc73086015 ("get rid of timer in kern/acct.c")
Reported-by: TSUKADA Koutaro 
Suggested-by: TSUKADA Koutaro 
Signed-off-by: Oleg Nesterov 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

acct: check FMODE_CAN_WRITE

2015-04-12T02:27:55+00:00

it's not calling ->write() directly anymore.

Signed-off-by: Al Viro

new fs_pin killing logics

2015-01-26T04:17:28+00:00

Signed-off-by: Al Viro

get rid of the second argument of acct_kill()

2015-01-26T04:17:27+00:00

Replace the old ns->bacct only with NULL and only if it still points
to acct.  And assign the new value to it *before* calling acct_kill()
in acct_on().  That way we don't need to pass the new acct to acct_kill().

Signed-off-by: Al Viro

take count and rcu_head out of fs_pin

2015-01-26T04:17:27+00:00

Signed-off-by: Al Viro

pull bumping refcount into ->kill()

2015-01-26T04:16:29+00:00

there will be one more change of ->kill() calling conventions; this
isn't final.

Signed-off-by: Al Viro

kill pin_put()

2015-01-26T04:16:28+00:00

Signed-off-by: Al Viro

acct: eliminate compile warning

2014-10-10T02:26:04+00:00

If ACCT_VERSION is not defined to 3, below warning appears:
  CC      kernel/acct.o
  kernel/acct.c: In function `do_acct_process':
  kernel/acct.c:475:24: warning: unused variable `ns' [-Wunused-variable]

[akpm@linux-foundation.org: retain the local for code size improvements
Signed-off-by: Ying Xue 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/acct.c: fix coding style warnings and errors

2014-08-07T18:40:09+00:00

Signed-off-by: Ionut Alexa 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro