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kobject_uevent: Fix OOB access within zap_modalias_env() 

commit dd6e9894b4 upstream.

zap_modalias_env() wrongly calculates size of memory block to move, so
will cause OOB memory access issue if variable MODALIAS is not the last
one within its @env parameter, fixed by correcting size to memmove.

Fixes: 9b3fa47d4a ("kobject: fix suppressing modalias in uevents delivered over netlink")
Cc: stable@vger.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Reviewed-by: Lk Sii <lk_sii@163.com>
Link: https://lore.kernel.org/r/1717074877-11352-1-git-send-email-quic_zijuhu@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Zijun Hu 2024-05-30 21:14:37 +08:00 committed by Greg Kroah-Hartman
parent f7150b2d5e
commit 57fe01d3d0
1 changed files with 16 additions and 1 deletions
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17
lib/kobject_uevent.c
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@ -432,8 +432,23 @@ static void zap_modalias_env(struct kobj_uevent_env *env)
len = strlen(env->envp[i]) + 1;
if (i != env->envp_idx - 1) {
/* @env->envp[] contains pointers to @env->buf[]
* with @env->buflen chars, and we are removing
* variable MODALIAS here pointed by @env->envp[i]
* with length @len as shown below:
*
* 0 @env->buf[] @env->buflen
* ---------------------------------------------
* ^ ^ ^ ^
* | |-> @len <-| target block |
* @env->envp[0] @env->envp[i] @env->envp[i + 1]
*
* so the "target block" indicated above is moved
* backward by @len, and its right size is
* @env->buflen - (@env->envp[i + 1] - @env->envp[0]).
*/
memmove(env->envp[i], env->envp[i + 1],
env->buflen - len);
env->buflen - (env->envp[i + 1] - env->envp[0]));
for (j = i; j < env->envp_idx - 1; j++)
env->envp[j] = env->envp[j + 1] - len;